UC-NRLF 


tED    MEb 


GIFT  OF 

PROF.  W.B.  RISING 


-v- 


THE 


STUDENTS'   GUIDE 


QUANTITATIVE  ANALYSIS 


INTRNDED  AS  AN  AID  TO  THE  STUDY  OF 


FRESENIUS'    SYSTEM. 


BY 


H.  CARRINGTON    BOLTON,  Ph.D., 

PROFESSOR    OF   CHEMISTRY    IN    TRINITY    COLLEGE, 
HARTFORD,    CONN. 


ILLUSTRATED. 


NEW  YORK : 
JOHN    WILEY   &   SONS. 

1882. 


COPYRIGHT, 

1881, 
BY  H.  CARKINGTON  BOLTON. 


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PREFA  CE. 


A  portion  of  the  following  pages  originally  appeared  in 
the  columns  of  the  American  Chemist,  under  the  title: 
"Schemes  of  Analyses  executed  in  tJie  School  of  Mines, 
Columbia  College!'  Numerous  applications  for  copies  in 
book  form  have  induced  the  author  to  publish  the  Schemes 
under  a  more  general  title. 

Since  writing  the  articles  the  author  has  been  called  to 
another  sphere  of  labor,  and  the  circumstances  which  led 
to  their  compilation  are  explained  in  the  following  para- 
graphs, quoted  from  the  prefatory  remarks  accompanying 
the  original  publication. 

"  The  system  of  instruction  in  Quantitative  Analytical 
Chemistry,  organized  in  the  School  of  Mines,  Columbia 
College,  by  Dr.  C.  F.  Chandler,  has  been  developed  by  the 
Assistants,  who  have  had  charge  of  the  Laboratory  for 
Quantitative  Analysis,  Mr.  Alexis  A.  Julien,  Dr.  Paul 
Schweitzer,  and  the  writer. 

The  practical  examples  and  the  methods  of  analysis  were 
originally  selected  by  Prof.  Chandler ;  the  latter  have  been 
modified  by  the  Assistants,  and  from  time  to  time  they 
have  introduced  new  processes,  conforming  to  the  advances 
made  in  this  department  of  chemical  science. 


VI  PREFACE. 

The  plan  of  the  STUDENTS'  GUIDE  is  similar  to  that 
in  the  excellent  papers  of  Mr.  Alexis  A.  Julien  entitled : 
"Examples  for  Practice  in  Quantitative  Analysis,"  the 
details,  however,  are  the  result  of  observing  the  needs  of 
students  during  my  five  years'  experience  in  teaching 
large  classes. 

The  fragmentary  character  of  many  portions  of  the 
notes  is  accounted  for  by  the  fact  that  they  are  intended 
to  serve  in  part  as  lecture  notes,  and  to  indicate  to  the 
student  the  points  to  be '  studied.  FRESENIUS'  "  System  of 
Instruction  in  Quantitative  Chemical  Analysis"  (American 
edition,  edited  by  Prof.  S.  W.  Johnson;  New  York,  1870) 
is  placed  in  the  hands  of  each  student  on  entering  the 
laboratory,  but  many  students  are  perplexed  by  the  peculiar, 
though  systematic,  arrangement  of  this  classic  work,  and 
are  at  a  loss  to  know  how  to  begin  work,  what  to  study,  and 
where  to  find  the  information  appropriate  to  particular 
cases.  To  aid  the  student  in  the  study  of  Fresenius'  work, 
and  not  to  displace  it,  is  one  of  the  objects  of  the  STUDENTS' 
GUIDE.  It  is  then  scarcely  necessary  to  state  that  very 
free  use  has  been  made  of  Fresenius  System;  acknowl- 
edgment is,  however,  made  in  all  cases.  By  occasional 
references  to  original  papers  the  student's  attention  is 
directed  to  methods,  as  detailed  by  their  authors,  with  the 
hope  of  encouraging  the  student  in  research." 

H.  C.  B. 

Trinity  College.  , 


LIST  OF  ANALYSES. 


List  of  Analyses. 

1.  Baric  chloride, 

2.  Magnesic  sulphate, 

3.  Ammonio-ferric  sulphate, 

4.  Potassic  chloride, 

5.  Hjdrodisodic  phosphate, 

6.  Silver  coin, 

7.  Dolomite, 

8.  Bronze, 

9.  Coal, 

10.  Copper  pyrites, 

11.  Alkalimetry, 

12.  Acidimetry, 

13.  Chlorimetry, 

14.  Type  metal, 

15.  Zinc  ore, 

16.  Chromic  iron  ore, 

17.  Pyrolusite, 

1 8.  Feldspar, 

19.  Slag, 

20.  Hematite, 

21.  Titaniferous  iron  ore, 

22.  Pig  iron, 

23.  Nickel  ore, 

24.  Arsenopyrite, 


Constituents  to  be  determined. 

Ba,  Cl,  H20. 

MgO,  SO3,  H2O. 

SO3,  NH3,  Fe2O3  by  ignition,  by  pre- 
cipitation and  volumetrically. 

K,  Cl, 

Na2O,  P2O6,  HaO  by  direct  weight. 

Au,  Ag,  Cu,  Pb. 

CaO,  MgO,  SiO2,  Fe2O3,  CO2  by  loss 
and  by  direct  weight. 

Cu,  Sn,  Zn. 

H2O,   volatile   matter,  fixed  carbon, 
ash,  S. 

Cu,  in  duplicate. 

Soda  ash,  pearl  ash. 

Vinegar,  hydrochloric  acid. 

Bleaching  powder. 

Pb,  Sn,  Sb,  Zn. 

Zn. 

Cr,08. 

MnO,. 

Si02,  A1208,  K,0,  Na20. 

SiO2,  A1,O3,  CaO,  MgO,  FeO,  MnO, 
S,  P208. 

SiO2,  Fe,  S  and  P. 

Complete  analysis. 

Fe,   Mn,   graphite,   combined  C,  P, 
S,  Si. 

Ni,  Co. 

As. 

vii 


Vlll 


LIST   OF  ANALYSES. 


List  of  Analyses.  Constituents  to  be  determined. 

P2O5,  CaO,  MgO,  Fe2O3,  SiO2,  H2O, 
NH3,  SO3,  organic  matter. 

P2O5  soluble,    precipitated,  and    in- 
soluble. 

CaO,   MgO,   Na20,    K2O,    SO3,    Cl, 

SiO2,  organic  matter. 
28.    Specific  gravity  of  a  solid,        Heavier,  lighter  than,  and  soluble  in 

water,  minerals  and  alloys. 

"     liquid,       By  the  flask,  by  hydrometer,  and  by 
weighing  a  s6lid  in  the  liquid. 

C,  H,  O. 

N    by  Willand    Varrentrapp's,    and 
Melsens'  methods. 

C,  H. 

Qualitative  and  quantitative. 

Water,  butter,  casein,  sugar,  ash. 

Water,     crystallizable     cane     sugar 
grape  sugar,  ash. 

Fractional  distillation,  specific  grav 
itjr,  fire  test. 


25.  Guano. 

26.  Superphosphate  of  lime, 

27.  Water, 


29 


30.  Sugar, 

31.  Potassic  ferrocyanide, 

32.  Oil  of  turpentine, 

33.  Urine, 

34.  Milk, 

35.  Raw  sugar, 

36.  Petroleum, 


INTRODUCTORY  NOTES. 


By  means  of  Chemical  Analysis  we  determine  the  com- 
position of  any  substance. 

The  object  of  Qualitative  Analysis  is  to  determine  the 
natiire  of  the  constituents  of  a  body. 

The  object  of  Quantitative  Analysis  is  to  determine  the 
amount  of  these  constituents. 

Quantitative  Analysis  includes  two  methods,  Gravimetric 
and  Volumetric  Analysis. 

In  Gravimetric  Analysis  we  convert  the  known  constitu- 
ents of  a  compound  into  such  forms  as  will  admit  of  their 
exact  determination  by  weight.  This  is  done  chiefly  in 
two  ways : 

ist.  By  separating  one  of  the  constituents  of  a  body  as 
such  (e.g.,  Cu  by  the  battery). 

2nd.  By  converting  an  existing  constituent  into  a  new 
form  by  exchange  of  elements  (e.g.,  AgNO3-[-HCl— AgC 
-j-HN03). 

The  forms  must  fulfil  two  conditions: 

ist.    Must  be  capable  of  being  weighed  exactly. 

2nd.    Must  be  of  known  and  fixed  composition. 


X  INTRODUCTORY    NOTES. 

The  choice  of  form  of  precipitate  depends  on  two  consid- 
erations. The  most  preferable  are — 

ist.   Those  most  insoluble  in  the  surrounding  liquid. 

2nd.  Those  in  which  the  proportion  of  the  constituents 
to  be  determined  is  very  small  compared  with  the  weight 
of  the  precipitate  (e.g.,  S  in  BaSO4  is  only  13.7  per  cent.). 

In  Volumetric  Analysis  the  amount  of  a  constituent  is 
estimated  by  the  action  of  reagents  in  solutions  of  known 
strength  and  of  determined  volumes.  (See  Notes  on  Vol- 
umetric Analysis,  p.  40). 


WORKS  FOR  REFERENCE  AND  FOR  STUDY. 


Eresenius.  A  System  of  Instruction  in  Quantitative  Chem- 
ical Analysis.  Editions:  Johnson's  American,  1870;  last 
English ;  last  German. 

Thorpe.  Quantitative  Chemical  Analysis.  New  York, 
1874. 

Rose,  H.  Traite*  Complet  de  Chimie  Analytique.  Paris, 
1859—62.  2  vols. 

Rose  H.,  and  Finkener.  Handbuch  der  Anatytischen 
Chemie.  Leipzig,  1867. 

Mohr.  Lehrbuch  der  Chemisch-analytischen  Titrirmeth- 
ode,  vierte  Auflage.  Braunschweig,  1874. 

Sutton.  Systematic  Handbook  of  Volumetric  Analysis. 
London,  1871  (2d  ed.). 

Rammelsberg.  Leitfaden  fur  die  Quantitative  Chemische 
Analyse.  Berlin,  1863. 

Crookes.  Select  Methods  in  Chemical  Analysis.  London, 
1871. 

Bolley  and  E.  Kopp.  Handbuch  der  Technisch-chemischen 
Untersuchungen.  Vierte  Auflage.  Leipzig,  1876. 

Wohler.  Die  Mineral  Analyse  in  Beispeilen.  Gottingen, 
1861.  Also  translation  by  Henry  B.  Nason.  Philadelphia, 
1871. 

Prescott.  Outlines  of  Proximate  Organic  Analysis.  Van 
Nostrand,  N.  Y,  1875. 

Caldwell.  Agricultural  Qualitative  and  Quantitative  Chem- 
ical Analysis.  New  York,  1869. 


Xll  WORKS    FOR    REFERENCE    AND    FOR    STUDY. 

Wanklyn.     Water  Analysis,  last  edition.     London. 

Bunsen.     Anleitung  zur  Analyse  der  Aschen  und  Mineral- 
wasser.     Heidelberg,  1874. 

Ricketts.     Notes  on  Assaying  and  Assay  Schemes.     New 
York,  1876. 

Storer.      First  Outlines  of  a  Dictionary  of  Solubilities  of 
Chemical  Substances.     Cambridge,  1864. 

Heppe.     Die  Chemische  Reactionen  der  wichtigsten  anor- 
ganischen  und  organischen  Stoffe.      (Tabellen,  etc.)  Leipzig, 

1875- 

Zeitschrift  fur  Analytische  Chemie,  Fresenius.    Wiesbaden, 
1862-1879. 

Jahresbericht  iiber  die  Fortschritte  der  Chemie.     Giessen, 
1847-77. 

Bulletin  de  la  Socie'te'  Chimique  de  Paris.      Paris,  1864-79. 
Chemical  News.     Crookes.     London,  1860-79. 
American  Chemist.     Chandler.     New  York,   1870-79. 

American  Journal  of  Science  and  Art.      J.  D.  and  E.  S. 
Dana.     New  Haven,  1819-1879. 


THE 
STUDENTS'   GUIDE 

IN 

QUANTITATIVE   ANALYSIS, 


Analysis  No.  i. —  BARIC  CHLORIDE. 
BaCl2  +  2H20. 

A.  —  Determination  of  Chlorine. 

See  Fres.  Quant.  Anal.,  §  141,  I,  a,  and  pages  564  to 
568.  (References  are  to  Fresenius'  Quantitative  Analysis, 
American  edition,  1870.) 

Weigh  out  0.8  to  i  grm.  of  powdered  BaCl2  +  2H2O  and 
dissolve  in  cold  water  in  a  beaker ;  add  a  slight  excess  of 
AgNO3  previously  acidulated  with  HNO3;  stir  well,  and 
warm.  When  the  precipitate  of  AgCl  has  entirely  settled, 
and  the  supernatant  liquid  is  quite  clear,  pour  off  through 
a  No.  2  filter;  then  add  boiling  water  slightly  acidulated 
with  HNO3,  to  the  precipitate  in  the  beaker;  stir,  and, 
after  the  precipitate  has  settled  again,  pour  off  through 
the  filter.  Continue  this  washing  by  decantation  three  or 
four  times ;  then  bring  the  precipitate  on  the  filter  by 
means  of  a  glass  rod  or  a  feather ;  wash  it  down  into  the 
point  of  the  filter;  wash  lastly  with  a  little  non-acidified 
water ;  cover  the  funnel  with  paper ;  label  properly,  and  set 
aside  to  dry.  Weigh  a  clean  porcelain  crucible ;  transfer 


14  QUANTITATIVE   ANALYSIS. 

the  precipitate  to  this  crucible,  removing  the  AgCl  from 
the  paper  as  completely  as  possible.  Wrap  a  clean  plati- 
num wire  around  the  rolled-up  filter,  forming  a  "cradle" 
burn  the  filter  in  the  cradle  over  the  inverted  crucible 
cover  ;  do  not  let  the  ashes  fall  into  the  crucible.  Moisten 
the  ashes  with  cone.  HNO3  (one  drop);  heat  one  minute; 
add  a  drop  of  cone.  HC1;  evaporate  cautiously,  and  heat 
the  contents  of  the  crucible  and  cover  until  the  AgCl  is 
partly  fused,  avoiding  carefully  a  higher  temperature  than 
necessary.  See  Fres.,  §  82,  b.  Weigh  the  crucible  and 
contents.  For  calculation,  see  D. 

AA. —  SECOND  METHOD. —  Compare  Fres.,  §  115, 1,  a,  /?. 
Take  to  0.2  to  0.5  grm.  BaCl2-l-  H2O;  dissolve  in  warm 
water;  acidulate  with  HNO3  (free  from  chlorine);  pour 
into  a  "parting  flask;"  add  AgNO3  in  slight  excess;  cork 
the  flask,  and  shake  well.  When  well  settled,  wash  the 
precipitate  in  the  flask  by  decantation  with  warm  water, 
without  filtering.  Invert  the  flask,  covered  with  a  watch- 
glass,  over  a  weighed  porcelain  crucible,  placed  in  a  large 
porcelain  dish,  and  filled  with  water.  Withdraw  the  watch- 
glass  carefully,  allow  the  precipitate  of  AgCl  to  fall  into  the 
crucible,  and  remove  the  parting  flask.  Pour  the  water  out 
of  the  crucible,  remove  the  last  portions  with  filter  paper, 
and  dry  on  a  water-bath.  Ignite  to  incipient  fusion,  and 
weigh. 

Note. —  The  precipitate  settles  best  in  presence  of  an 
excess  of  AgNO3. 

B.— Determination  of  Barium. 

See  Fres.,  §  132, 1,  i,  and  §  101,  I,  a.  Dissolve  i  to  1.5 
grm.  substance  in  warm  water  ;  acidulate  with  HC1 ;  dilute 
to  about  250  c.c.;  heat  to  boiling ;  when  boiling  hard,  add 
dilute  HaSO4  in  slight  excess ;  boil  some  minutes  and  then 


CALCULATION    OF    ANALYSIS  15 

keep  warm  while  the  precipitate  settles.  Test  with  a 
drop  of  H2SO4 ;  wash  with  boiling  water  by  decantation  ; 
then  bring  the  precipitate  on  a  No.  2  filter ;  wash  well ;  dry 
and  ignite  precipitate  in  a  platinum  crucible ;  burn  filter  in 
a  cradle  as  above,  and  add  ashes  to  contents  of  crucible. 
See  Fres.,  §  71,  a. 

Note.  —  Wash  until  the  filtrate  gives  no  precipitate  with 
AgNO3.  When  estimating  barium  in  the  presence  of 
nitrates,  chlorides,  etc.,  these  salts  are  sometimes  carried 
down  with  the  BaSO4.  Since  it  is  impossible  to  remove 
these  by  washing  with  water  alone,  treat  the  precipitate 
with  very  dilute  HC1,  or  ammonic  acetate.  Cf.  Crookes' 
Select  Methods,  page  3 1 2. 

C.  Determination  of  Water  (by  Ignition).— 

In  a  weighed  crucible  weigh  out  I  to  1.5  grms.  substance ; 
heat  very  gently  at  first  over  a  small  flame,  and  increase 
the  temperature  very  gradually ;  finally,  heat  to  low  redness ; 
then  cool,  weigh,  and  repeat  the  operation  until  the  weight 
remains  constant.  Caution  :  avoid  too  high  a  temperature, 
else  the  Cl  will  be  expelled.  When  substances  contain  large 
percentages  of  water,  as  magnesic  sulphate,  hydrodisodic 
phosphate,  alum,  etc.,  begin  to  expel  the  water  at  100°  C. 
in  an  air-bath. 

D.  Calculation  of  Analysis.— 

See  Fresenius,  page  568,  also  §  196.  Make  two  state- 
ments, the  first  to  determine  the  amount  of  the  desired 
constituent  in  the  precipitate  obtained : 

TVT  i   \\T4-     f  )       At.  Wt.  of  the   1  Actual         )  Actual       ) 

Mol.Wtof    I     .    constituent       I    =    weight  of      V    :    weight  of    [ 
precipitate    J  degired          J          precipitate     j       constituent.! 


l6  QUANTITATIVE    ANALYSIS. 

The  second  statement  determines  the  percentage  of  the 
desired  constituent  in  the  substance  taken : 


Wt.  of  sub- 
stance taken 


}.  Actual  weight  of    ]     _         .    Percentage  of  the 
constituent  constituent. 

To   check  work,  compare  with  theoretical  percentages 
when  possible. 

Theoretical  composition  of  crystallized  barium  chloride. 


C12  =  29.09 
2H2O=  14.76 


IOO.OO 


Use  of  Presetting  Tables  for  the  calculation  of  analyses. 
Compare  Table  III,  Fres.,  page  608. 

Examples:        Fe2O3  X  0.7  =  2Fe. 

BaOSO3  X  0.34335  = 


Consult  Table  IV,  Fres.,  pages  610,  et  seq.,  also  page  464. 

Example:  1.2685  grms.  MgSO4  yielded  a  precipitate 
of  BaSO4,  which  weighed  1.2074  grms.  From  the  table 
we  have: 


.2     

0.06867 

.OO    

o.ooooo 

.007 

.  0.00240 

.0004 0.00013 


1.2074 

0.41455 

=32.78  per  cent.  SO3 

1.2685 


REPORTING     ANALYSES.  1 7 

E.  Reporting1  Analyses. — 

Analyses  may  be  reported  on  blank  forms  printed  on  let- 
ter paper  8"  x  10",  having  following  headings  : 

HARTFORD, ,  188  .  REPORT  OF  .  ANALYSIS 

OF  .  DETERMINATION  OF  .  GRAMMES  TAKEN 

.  METHOD  OF  ANALYSIS .  These  headings  are 

printed  in  vertical  column ;  in  one  horizontal  line 
are  placed  following  headings :  PRECIPITATES,  ACTUAL 
WEIGHTS,  CONSTITUENTS,  CALCULATED  WEIGHTS,  PER- 
CENTAGES, THEORETICAL  PERCENTAGES  ;  under  each  a  blank 
space  is  left  of  2  1-2  inches.  Under  "  precipitates  "  place 
formulae  of  precipitates  obtained ;  under  "  actual  weights  " 
place  actual  weights  of  precipitates  ;  under  "  constituents  " 
place  formulae  of  constituents  to  be  reported ;  under  "  cal- 
culated weights  "  place  the  amounts  of  constituents  existing 
in  precipitates;  under  "percentages"  place  percentages  of 
constituents  actually  obtained  —  in  short,  the  results  of 
analyses.  The  last  column,  "  theoretical  percentages,"  can 
be  filled  only  in  the  case  of  few  pure  chemical  salts. 

The  words  SPECIAL  REMARKS  are  printed  about  two  inches 
from  the  bottom  of  the  sheet,  leaving  room  for  remarks  on 
processes  employed,  etc.* 

Notes  to  the  Analysis  of  Barium  Chloride. 

Reactions,  (i)  BaCl2  +  H2SO4  =  BaSO4  -f  2HC1. 

(2)  BaCl2  +  2AgNO3  =  2AgCl  +  Ba(NO3)2. 

The  chloride  of  silver  precipitate  changes  color  on  expos- 
ure to  light,  losing  chlorine  and  forming  Ag2Cl ;  the  change, 
however,  is  only  superficial,  but  Mulder  says  the  loss  of 
weight  is  appreciable. 

*  See  specimen  blank  at  the  end  of  this  book. 


1 8  QUANTITATIVE    ANALYSIS. 

When  one  part  of  silver  is  thrown  down  as  AgCl  in 
1,000,000  parts  of  water,  a  slight  bluish  milkiness  may  still 
be  seen.  This  cloudiness  disappears  on  adding  an  excess 
of  HC1. 

Barium  sulphate  requires  more  than  400,000  parts  of 
water  for  solution.  The  solubility  is  not  perceptibly 
increased  by  the  presence  of  NaCl,  KC1O3  or  Ba(NO3)2, 
but  HC1  produces  a  sensible  increase.  (Cf.  Storer's  Diction- 
ary of  Solubilities^) 

Barium  sulphate  thrown  down  in  a  solution  containing 
ferric  salts  is  often  contaminated  with  iron.  This  becomes 
evident  by  the  reddish  color  of  the  precipitate  after  ig- 
nition. The  precipitate  may  be  purified  by  washing  with 
ammonium  acetate,  or  by  solution  in  cone.  PLSO4,  and  re- 
precipitation  by  pouring  into  water.  BaSO4  dissolves  in 
cone.  H2SO4  in  the  ratio  of  5.7  parts  to  100,  and  in  Nord- 
hausen  sulphuric  acid  as  15.9  to  100. 


Analysis  No.   2. — MAGNESIC  SULPHATE. 
MgS04+;H20. 

A.  —  Determination  of  Sulphuric  Acid. 

See  Fres.,  §  132,  I,  I.  Dissolve  i  to  1.5  grm.  of  sub- 
stance in  warm  water,  acidulate  with  HC1,  dilute  to  about 
250  c.c. ;  boil  hard ;  add  BaCl2  carefully,  avoiding  a  large 
excess ;  boil  a  few  minutes ;  let  the  precipitate  of  BaSO4 
settle  ;  wash  by  decantation  and  on  the  filter,  and  continue 
as  in  Analysis  I,  B. 

B.  —  Determination  of  Magnesium. 

Fres.,  §  104,  2.  —  Dissolve  about  1.2  grm.  of  substance 
in  150  c.c.  cold  water,  in  a  beaker;  add  30  c.c.  NH4C1, 


DETERMINATION     OF     WATER.  IQ 

10  c.c.  NH4HO,  and  a  slight  excess  of  HNa2PO4.  (Should 
a  precipitate  form  on  adding  NH4HO,  add  NH4C1  until  it 
redissolves.)  Stir  the  contents  of  the  beaker  well,  avoiding 
touching  the  sides  with  the  glass  rod.  Cover,  and  set  aside 
for  12  hours,  without  warming.  Filter  and  wash  with  cold 
water,  to  which  one-fourth  its  volume  of  NH4HO  has 
been  added,  until  the  filtrate  acidified  with  HNO3  gives 
only  a  slight  opalescence  with  AgNO3.  Dry  thoroughly  on 
the  filter,  ignite  in  a  platinum  crucible,  gradually  increasing 
the  heat ;  burn  the  filter  on  a  cradle  until  quite  white  before 
adding  the  ashes  to  the  contents  of  the  crucible.  If  the  pre- 
cipitate or  ash  is  not  white,  moisten  with  a  drop  or  two  of 
cone.  HNO3,  evaporate,  and  ignite  cautiously.  (See  Fres., 
§  74,  b  and  c.)  Weigh  the  precipitate  as  Mg2P2O7. 

C.  —  Determination  of  "Water. 

Heat  i  to  1.5  grm.  salt  in  a  weighed  platinum  crucible, 
and  proceed  exactly  as  in  Analysis  I,  C. 

Notes  to  Analysis  of  Magnesia  Sulphate. 

On   the   solubility  of  ammonio-magnesic   phosphate  in 
water  and  saline  solutions.    Cf.  Fres.  page  587,  paragraphs 

31-35. 

f  1 5300  parts  of  pure  water. 

One  part  of    |  443°°     "       "   ammoniated  water, 
precipitate    4     7548     "       "   strong  sol.  of  NH4C1. 
dissolves  in       15600     "       "   water  containing   NH4HO 

[   '  andNH4Cl. 

Fresenius's  proposed  correction  of  o.ooi  grm.  magnesic 
pyrophosphate  for  every  54  c.c.  of  filtrate  is  stated  to  be 
incorrect. 


2O  QUANTITATIVE   ANALYSIS. 

Reactions. — By  precipitation  we  have  : 

2MgSO4  +  NH4C1  +  2NH4HO  +  2HNa2PO4= 
Mg2(NH4)2P208  +  NH4C1  +  2Na2S04  +  2H2O. 

On  heating  we  have : 

(NH4)2Mg2P208  =  Mg2P207  +  2NH3  +  H2O. 

Theoretical  Composition — 


so,  . 

.    12  ^2. 

7H2O   

.    ^1.22 

IOO.OO 

Analysis  No.  3. — AMMONIA-! RON- ALUM. 
Fe2(NH4)2(S04)4+24H20. 

A.  — Determination  of  Sulphuric  Acid. 

Dissolve  I  gr.  to  1.5  grms.  in  water,  add  5  c.c.,  dilute 
HC1  to  prevent  ferric  hydrate  from  precipitating  with  the 
BaSO4,  heat  to  boiling,  add  BaCl2  and  proceed  exactly  as 
in  Analysis  2,  A. 

B.—  Determination  of  Ammonium. 

(Fres.,  §  99,  b,  2,  0.) 

(i.)  Dry  the  salt,  if  necessary,  before  weighing,  by  press- 
ing the  powder  between  folds  of  bibulous  paper.  Dissolve 
about  1.5  grms.  in  a  little  cold  water  in  a  casserole,  add  a 
little  dilute  HC1  and  an  excess  of  PtCl4.  Evaporate  nearly 
to  dryness  on  a  water-bath  scarcely  heated  to  boiling.  Add 


DETERMINATION    OF    IRON  21 

50  to  80  c.c.  alcohol  to  the  casserole  while  still  warm  ;  do 
not  stir ;  let  stand  several  hours.  The  supernatant  liquid 
should  be  colored  by  an  excess  of  PtCl4. 

(2.)  Place  a  No.  I  Swedish  filter  in  a  small  funnel,  wash 
with  very  dilute  HC1,  then  with  water  thoroughly;  dry  in 
the  funnel,  then  remove  the  filter  and  place  it  on  watch- 
glasses  with  clip;  dry  in  an  air  bath  100°  C.  exactly,  for 
one  hour  precisely ;  then  close  glasses  and  weigh  the  whole. 

(3.)  Bring  the  yellow  crystalline  precipitate  on  the 
weighed  filter  by  means  of  a  clean  feather,  wash  with  al- 
cohol carefully,  not  too  much,  dry  on  funnel.  Then  trans- 
fer to  clip,  dry  at  100°  C.  as  before,  and  weigh.  Dry  and 
weigh  again,  repeating  until  constant ;  calculate  results. 

Precipitate  has  the  composition  (NH4)2PtCl6. 

[In  the  case  of  potassium  determinations,  wash  with  a 
mixture  of  alcohol  and  ether ;  also  concentrate  filtrate  and 
washings,  filter  from  the  secondary  precipitate  and  add  to 
the  former.] 

(4.)  Transfer  the  precipitate  to  a  weighed  crucible,  burn 
the  filter  and  add  the  ashes ;  ignite  gradually  and  strongly. 
Weigh  the  Pt  remaining  as  a  check  on  the  first  determi- 
nation. 

[In  the  case  of  potassium,  add  a  little  oxalic  acid  in  pow- 
der to  the  contents  of  the  crucible,  ignite,  wash  residue 
with  water,  dry  on  water-bath,  ignite,  and  weigh.  (See 
Fres.,  §  97,  3,  ft.)] 

For  solubility  of  ammonio-platinic  chloride,  see  Fres. 
p.  584,  paragraph  16. 


<J.  —  Determination  of  Iron. 

I.   By  Ignition, — (Fres.,  §  113,  i,  e.)  Expose  i.o  grm.  of 
the    salt   in   a   weighed    covered    platinum,    or    porcelain 


22  QUANTITATIVE    ANALYSIS. 

crucible,  to  a  moderate  heat,  gradually  raise  the  temper- 
ature till  all  the  water  is  expelled  ;  then  heat  intensely  be- 
fore the  blast-lamp.  Weigh  the  residue  as  Fe2O3  ;  heat 
and  weigh  again.  Test  the  residue  for  H2SO4. 

II.  BY  PRECIPITATION.  —  (Fres.,  §  113,  i,  a.)  Dissolve 
about  I  grm.  of  the  salt  in  question  in  a  large  beaker  with 
about  250  to  300  c.c.  of  water,  acidify  with  HC1,  heat  nearly 
to  boiling,  add  NH4HO  in  excess;  let  settle  after  stirring; 
wash  hot  by  decantation.  (N.B.  —  Wash  out  NH4C1  com- 
pletely, lest  on  subsequent  ignition  a  portion  of  the  iron 
volatilize  as  chloride.  One  grm.  of  ferric  hydrate  requires 
nearly  one  gallon  of  water.)  Bring  precipitate  on  filter,  dry 
thoroughly  on  funnel,  ignite  and  weigh.  Burn  filter  and 
precipitate  separately.  (See  Fres.,  §  53.) 

Ammonia  acts  on  the  ferric  solution  in  accordance  with 
the  equation  : 


2[Fe2(S04)3]  +  I2NH4HO  =  2Fe2O33H2O  + 
6[(NH4)2S04]  +  3H20. 

III.  DETERMINATION  OF  IRON  BY  MARGUERITE'S  METH- 
OD. —  See  Fres.,  §  1  12,  2,  a.  Compare  Mohr's  Titrirmethode, 
pages  1  80  to  204,  also  Crookes'  Select  Methods,  page  73. 

(i.)  Standardisation  of  the  Solution  of  Potassium  Per- 
manganate. —  Dissolve  13  grms.  K2Mn2O8  in  two  litres  of 
distilled  water,  shake,  let  settle  over  night,  and  siphon  off 
into  a  bottle.  Fill  a  Gay-Lussac  burette  with  this  solution 
up  to  the  zero  mark. 

Dissolve  exactly  0.2  grm.  of  piano-forte  wire,  previously 
cleaned  with  sand-paper,  in  a  closed  flask  with  cone.  H2SO4 
and  sufficient  water.  Boil  until  dissolved  ;  cool  suddenly 
under  the  faucet,  but  to  avoid  collapse  of  flask  wait  a  few 


DETERMINATION    OF    IRON.  23 

moments  before  allowing  the  cold  water  to  fall  upon  it. 
The  flask  should  be  provided  with  a  Kronig  caoutchouc 
valve.  This  is  made  by  inserting  a  short  glass  tube  through 
a  cork  in  the  neck  of  the  flask,  and  fitting  to  the  projecting 
end  of  the  tube  a  piece  of  caoutchouc  tubing  about  10  cm. 
long.  A  slit  4  to  5  cm.  long  is  cut  lengthwise  in  the 
caoutchouc  tubing,  and  the  open  end  stopped  with  a  piece 
of  glass  rod.  The  valve  is  then  complete.  (Fig.  i.) 


FIG.  x. 


FIG.  2. 


In  place  of  the  Kronig  valve,  another  form  may  be  used. 
The  projecting  end  of  the  glass  tube,  fitted  to  the  cork  in 
the  neck  of  the  flask,  is  passed  through  another  cork  until 
just  even  with  its  surface.  Over  the  end  of  the  cork  and 
tube  a  small  piece  of  sheet  caoutchouc  is  fastened  by  means 
of  pins,  the  rubber  acting  as  the  valve.  (Fig.  2.)  Having 
effected  the  complete  solution  of  the  iron  wire  in  one  of 


24  QUANTITATIVE    ANALYSIS. 

these  flasks,  pour  the  solution  into  a  large  beaker  contain- 
ing about  300  to  400  c.c.  H2O,  placed  upon  a  sheet  of 
white  paper ;  wash  flask  carefully,  and  add  to  beaker.  Now 
pour  the  solution  of  K2Mn2O8  from  the  burette,  drop  by 
drop,  stirring  continually,  and  continue  until  the  pink  hue 
first  permanently  colors  the  whole  liquid.  Read  the  burette 
and  calculate  as  follows  for  the  standard : 

c.c.  used :  I  c.c.  =•  grms.  Fe  :  x,  or  standard. 

Repeat  the  titration  until  two  concordant  results  are  ob- 
tained. Correction :  To  allow  for  the  impurities  in  the 
iron,  multiply  the  amount  taken  by  0.997. 

(2.)  Reduction  of  the  Ferric  Solution.  —  Dissolve  4.0 
grms.  ammonia-iron-alum  in  water,  dilute  to  exactly  500 
e.c. ;  mix  well,  and  divide  in  halves. 

Place  a  piece  of  amalgamated  zinc  and  a  strip  of  plat- 
inum foil  in  each  reduction  bottle ;  pour  in  the  solutions 
and  washings ;  add  a  little  cone.  H2SO4,  and  cover  the 
bottles  with  watch  glasses.  The  reduction  requires  six  to 
eight  hours.  If  the  platinum  foils  are  new,  scour  them 
with  silica,  rub  them  with  KHO  solution,  then  with  HNO3, 
and  wash  carefully.  Removal  of  the  polished  and  possibly 
greasy  surface  hastens  the  evolution  of  hydrogen  and  con- 
sequently the  reduction. 

Reaction  : 
Fe2(S04)3+Zn+H2S04^2(FeS04)+ZnS04+H2S04. 

(3.)  Performance  of  the  Analysis. — When  the  reduction 
is  complete,  ascertained  by  testing  a  few  drops  with  am- 
monium sulphocyanide,  pour  the  contents  of  each  reduction 


DETERMINATION     OF     IRON.  2  5 

bottle  into  a  large  beaker,  add  H2SO4,  and  K2Mn2O8  from 
the  burette  until  a  permanent  pink  color  is  obtained.  (See 
Fres.,  §  112,  2,  a.)  The  two  determinations,  one  in  each 
bottle,  should  not  vary  more  than  0.2  per  cent. 

(4.)  Calculation  of  tJie  Analysis.  No.  of  c.c.  used  X 
standard  =  a  or  amount  Fe. 

a  X  ioo  r  . 

— — —  =  per  ct.  of  iron. 

wt.  of  salt  taken 

IV.       THE    STANDARD     OF     THE     SOLUTION     of     potassium 

permanganate  may  be  determined  in  several  ways. 

(a.)  Mohrs  Method. — Weigh  out  1.4  grm.  ainmonio- 
ferrous  sulphate,  dissolve  and  titrate  as  usual.  One-seventh 
of  its  weight  =  iron.  Ammonio-ferrous  sulphate  =  FeSO4 
+  (NH4)2S04  +  6H20. 

In  both  this  and  the  preceding  method  the  reaction  is 
the  same. 

ioFeS04+8H2S04+K2Mn208^5Fe,(S04)3+K2S04+ 
2MnS04  +  8H20. 


(£.)    HempeVs  Method.  —  Weigh   out   6.3    grms.    pure, 
dry   oxalic    acid,    dissolve   in   one  litre  of   water,   making 

N 

a  decinormal  (  —  -}  solution.      Dilute  50  c.c.  of  this  solu- 
V  10' 

tion,    add   6   to    8    c.c.    cone.    H2SO4,    warm   and  titrate. 
The  reaction  in  this  case  is  as  follows  : 


5H2C204  +  3H2S04  +  K2Mn208  =  ioCO2  +  2MnSO4 
K2SO4+8H2O. 


26  QUANTITATIVE    ANALYSIS. 

D-  —  Determination  of  Water. 
Water  may  be  determined  by  difference. 

Theoretical  composition  : 

(NH4)20=  5-39 
Fe2O3=i6.6o 


100.00 

Analysis  No.  4.  —  POTASSIUM  CHLORIDE. 
KC1. 

Expel  hydroscopic  moisture  carefully  by  heating  and 
stirring  in  a  porcelain  dish  over  a  Bunsen  burner,  before 
filling  the  weighing  tube. 

A.  —  Determination  of  Chlorine. 

Dissolve  about  0.8  grm.  in  warm  water  and  proceed  ex- 
actly as  in  Analysis  No.  I,  A. 

B.  —  Determination  of  Potassium. 

See  Fres.,  §  97,  3,  a,  and  Crookes'  Select  Methods,  page  i. 

Dissolve  about  0.5  grm.  in  a  little  cold  water  in  a  casse- 
role, and  proceed  exactly  as  in  the  determination  of  ammo- 
nia, Analysis  No.  3,  B,  paying  especial  attention  to  tlie  sen- 
tences in  brackets. 

For  solubility  of  potassio-platinic  chloride,  see  Fresenius' 
Quant.  Analysis,  p.  583,  paragraph  No.  8. 


DETERMINATION    OF    SODIUM.  27 

Theoretical  composition  : 

K 52-41 

Cl 47-59 


IOO.OO 


Analysis  No.  5. —  HYDRODISODIC   PHOSPHATE. 
Na2HPO4+i2H2O. 

A- —  Determination  of  Sodium. 

Cf.  Fres.,  §  135,  a,  /?. — Dissolve  about  i  grm.  salt  in  200 
c.c.  water  in  a  large  beaker. 

Weigh  off  about  0.6  grm.  clean  piano-forte  wire,  place  in 
a  flask,  add  cone.  HC1  with  some  HNO3,  boil  hard  (undei 
a  hood);  when  fully  dissolved,  continue  boiling  until  excess 
of  HNO3  is  removed,  then  dilute,  and,  if  necessary,  filter 
through  a  filter  previously  washed  with  dilute  HC1. 

Add  this  solution  of  pure  Fe2Cl6  to  that  of  the  hydrodiso- 
dic  phosphate,  and  immediately  an  excess  of  NH4HO. 
Heat  and  let  the  precipitate  stand  some  hours ;  wash  by 
decantation  with  boiling  water  very  thoroughly.  Evap- 
orate the  filtrate  with  a  slight  excess  of  dilute  HC1  on 
a  water-bath  to  dryness.  Heat  with  care  until  fumes 
of  NH4C1  cease  to  come  off;  dissolve  the  residue  in 
water ;  filter  through  a  very  small  filter  into  a  small 
weighed  dish,  platinum  preferred.  Add  a  few  drops 
of  dilute  HC1;  evaporate  to  dryness  on  a  water-bath; 
ignite  very  cautiously,  not  too  long,  and  weigh  the  NaCl. 
If  the  residue  is  not  perfectly  white  and  soluble  in  water 
without  residue,  dissolve,  filter  through  a  very  small  filter 
into  another  weighed  dish.  Evaporate  and  ignite  again. 
Test  residue. 


28  QUANTITATIVE    ANALYSIS. 

B.  —  Determination  of  Phosphoric  Acid. 

Fres.,  §  134,  I,  b,  a.  —  Dissolve  about  1.2  grms.  of  the 
salt  in  question  in  cold  water ;  add  "  magnesia  mixture  "  in 
excess  and  NH4HO;  set  aside  for  twelve  hours,  and  then 
continue  exactly  as  in  Analysis  No.  2.  Consult  Fres., 
Exp.  32,  p.  587. 

C.— Determination  of  "Water. 

(1)  By  ignition. — Weigh  out  about  0.8  gramme;  place 
it  in  a  weighed  crucible,  in  an  air-bath,  until  partially  de- 
hydrated ;  then  heat  cautiously  over  a  Bunsen  burner,  ig- 
nite eventually  to  redness,  and  weigh. 

(2)  By  direct  weight. — Weigh  out  about  0.7  gramme 
substance,  and  introduce  it  into  the  weighed  ignition  bulb 
by  means  of  a  very  narrow  piece  of  folded  paper.     Weigh 
CaCl2  tube,  and  'arrange  apparatus,  as  shown  in  Fig.  25, 
page  45>of  Fres.  Quant.  Analysis  (American  edition,  1870), 
substituting  aspirator  for   gasometer   if  more  convenient. 
Heat  cautiously,  aspirating  continually,  and  raise  the  tem- 
perature to  a  low  red  heat  for  three  minutes.     In  driving 
the  water  into  the  CaCl2  tube  be  careful  not  to  burn  the 
cork.      Aspirate  while  cooling,  not  too  rapidly.      Weigh 
CaCl2  tube  after  cooling  and  the  ignition  bulb  as  a  check. 
Consult  Fres.,  §  36,  page  45. 

Theoretical  Composition  : 

When  water  is  determined  by  heating  to  redness,  the 
calculation  must  be  based  on  two  molecules  of  the  salt. 

2Na2O—  17.32 
Pa05=  19.83 

=:  62.85 


100.00 


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ANALYSIS    OF    DOLOMITE.  3! 

Note  2. — If  it  is  desirable  to  determine  the  SiO2  in  the 
silicates  present,  "  Residue  a"  must  be  treated  as  follows  : 
Dry  and  ignite  (with  filter),  mix  in  a  platinum  crucible  with 
about  six  parts  of  Na2CO3  (anhydrous),  and  fuse  at  a  red 
heat.  Cool,  remove  the  fused  mass  with  boiling  water,  add 
an  excess  of  HC1,  evaporate  to  dryness  on  a  water-bath, 
heat  in  an  air-bath  until  the  HC1  is  completely  expelled  ; 
again  moisten  with  HC1,  dissolve  in  water,  and  filter  from 
the  residue.  The  residue  which  is  now  pure  hydrated  SiO2, 
is  dried,  ignited,  and  weighed.  The  filtrate  must  be  added 
to  "Filtrate  a"  Examine  Fres.,  §  140,  II,  b,  a,  and  §  93,  9. 

Note  3.— Heat  the  filtrate  from  "  Residue  a"  add  NH4C1, 
and  NH4HO  in  slight  excess.  (The  NH4C1  may  be  omit- 
ted if  the  "  Filtrate  a  "  is  very  acid.)  Heat  until  excess  of 
NH4HO  is  expelled,  filter  quickly,  and  wash  hot.  See  Fres., 
§  113,  \,a,and\  105,  I,  a. 

Note  4. — "  Precipitate  b  "  is  partly  washed,  and  then,  while 
moist,  dissolved  in  a  little  warm  dilute  HC1  on  the  filter,  the 
solution  is  reprecipitated  by  NH4HO  and  the  precipitate 
brought  on  the  same  filter,  washed  thoroughly,  dried,  and 
ignited.  Weigh  as  Fe2O3+Al2O3.  The  second  filtrate  is 
added  to  "  Filtrate  &" 

Note  5. — Concentrate  "  Filtrate  b"  add  some  NH4C1  un- 
less present  already,  add  (NH4)2  C2O4  in  considerable  ex- 
cess, and  some  NH4HO.  Let  stand  12  hours  in  a  warm 
place.  Wash  partially  and  filter.  See  Fres.,\  154,  6,  #; 
also  §  103,  2,  b,  a. 

Note  6. — Dissolve  the  partially  washed  "  Precipitate  c  " 
in  HC1,  reprecipitate  with  NH4HO  and  a  little  (NH4)2C2O4. 
Filter  and  wash  hot,  add  filtrate  and  washings  to  "  Filtrate 
c?  Dry  precipitate  on  funnel,  transfer  to  crucible,  burn  fil- 
ter, add  ashes,  add  a  few  drops  of  cone.  H2SO4  to  contents  of 


32  QUANTITATIVE    ANALYSIS. 

crucible,  ignite  cautiously  to  low  redness,    and  weigh   as 
CaSO4.     Compare  Fres.,  §  103,  2,  b,  a. 

Note  7. — If  care  has  been  taken  to  avoid  undue  excess  of 
NH4C1  in  the  preceding  steps,  the  magnesium  may  be 
thrown  down  in  " Filtrate  c"  immediately.  Otherwise  the 
NH4C1  must  be  expelled  as  follows  :  Concentrate  the  liquid, 
add  3  grms.  of  HNO3  for  every  grm.  of  NH4C1  supposed 
to  be  in  the  solution,  warm  gently  (60°  C.)  and  eventually 
heat  to  boiling. 

Concentrate  "  Filtrate  c"  add  NH4HO  and  Na2HPO4 
and  proceed  as  in  Analysis  2.  B.  See  Fres.,  §  104,  2,  and 
§74- 

Notes  on  the  Decomposition  of  NH4C1  by  HNO3  in  solu- 
tion. Comptes  Rendus,  October  13,  1851  (Maumene). 
J.  Lawrence  Smith  in  American  Chemist,  Vol.  Ill,  p.  201. 
Also  Am.  Jour.  Sci.  (2),  Vol.  15,  note,  page  240,  which  is  as 
follows  :  "  The  character  of  the  decomposition  which  takes 
place  is  somewhat  curious  and  unexpected :  it  was  first 
supposed  that  equal  volumes  of  Cl,  N2O,  and  N  were  given 
off,  but  it  is  shown  that  nearly  all  the  NH4HO,  with  its 
equivalent  of  HNO3,  is  converted  into  N2O,  the  liberated 
HC1  mixing  with  the  excess  of  HNO3.  A  little  of  the 
NH4Cl-f-HNO3  does  not  undergo  the  decomposition  first 
supposed,  and  in  this  way  only  can  the  small  amounts  of  N 
and  Cl  be  accounted  for."  "  Some  nitrous  or  hyper-nitrous 
acid  forms  during  the  whole  process  if  cone.  HNO3  is  used, 
little  or  none  if  dilute  HNO3." 

The  action  of  NH4NO3  on  NH4C1  is  theoretically  as 
follows : 

2(NH4NO3)+NH4Cl=5N+Cl+6HaO. 


ANALYSIS    OF    DOLOMITE.  33 

The  following  are  possible  reactions  : 

8NH4Cl+ioHNO3=  9N2O+8Cl  +  2iH2O, 

2HN03+2NH4C1=N20+2C1+2N+5H20, 

HN03+NH4C1=HC1+N20+2H20, 

and 
2HN03+NH4C1=N20+C1+N02+3H2O, 

and 
=NO  +  C1+NOC12+N02+4C1+5H20. 


Note  8.     Determination  of  CO2.  —  /.  By  loss.    Fres.,  §  139, 
II.,  d,  bb,  and  cc. 

Weigh  out  i.o  to  2.0  grms.,  place 
in  the  Geissler  apparatus,  fill  the 
proper  portions  of  the  apparatus  with 
HC1  (dil.)  and  with  H2SO4  (cone.) 
respectively.  Weigh  apparatus.  Cau- 
tiously let  the  HC1  flow  on  the  min- 
eral, warm  gently,  heating  at  the  last 
till  the  solution  begins  to  boil.  '  Cool 
apparatus  and  weigh.  For  details 
consult  Fresenitts,  as  above.  Do  not 
hurry  this  process  too  much.  Fi 

//.  —  By  direct  weight.     Consult  Fres.,  §  139,  II.,  c. 

Arrange  apparatus  as  in  Fig.  4.     Suspend  tubes  by  wire 
tloops  on  nails. 

a  contains  soda-lime. 
c  is  a  flask  of  about  200  c.c.  capacity. 
d  contains  cone.  H2SO4. 

e  contains  pieces  of  pumice-stone  saturated  with   cone. 
H2SO4  ;  avoid  much  liquid  in  the  bend. 
/contains  pumice-stone  saturated  with  anhydrous  CuSO, 


34 


QUANTITATIVE    ANALYSIS. 


N.B. — Make  a  strong  hot  solution  of  CuSO4-j-5H2O,  add 
pieces  of  pumice-stone,  Soil  hard,  evaporate  to  dryness  and 
ignite  well.  The  product  should  be  nearly  white. 

g  contains  in  outer  tube,  soda-lime  ;  in  inner  tube,  (h) 
pumice-stone  saturated  with  H2SO4  ;  weigh  these  together 
both  before  the  absorption  and  after. 


Fig.  4. 

Place  i.o  to  1.5  grms.  mineral  in  c,  weigh  g  and  h,  and 
connect  apparatus  ;  a  is  not  attached  at  first.  Pour  a  little 
water  through  the  funnel  tube  into  c,  then  add  gradually 
HC1,  diluted  one-half  with  water.  Attach  a,  and  aspirate 
gently.  Heat  cautiously  to  incipient  ebullition  ;  maintain 
this  a  few  moments,  and  let  cool  while  the  aspiration 
continues.  Weigh  —  increase  of  weight  gives  CO2. 

Note  9.     Calculation. — Normal  dolomite  contains  : 

30.4  per  cent.  CaO. 
47.8  «  CO,,. 
21.8  "  MgO. 


i  oo.o 


Having    estimated     these    constituents,    calculate    the 


ANALYSIS    OF     BRONZE.  35 

amounts  of  CaCO3  and  MgCO3,  and  report  under  "  Special 
Remarks,"  thus  : 

CaO :  CO2  =  CaO  found  :  CO2  required  or  M. 
MgO  :   CO2  =  MgO  found :    CO2  required  or  N. 
and  M  -f-  N  must  —  CO2  found,  nearly. 


Analysis  No.  8  —  BRONZE. 
To  be  determined,  Sn,  Pb,  Cu,  Zn. 

A.— Determination  of  Tin. 

Dissolve  about  0.6  grm.  bronze  filings,  carefully  freed 
from  accidental  impurities,  in  moderately  dilute  HNO3,  in 
a  flask  in  the  neck  of  which  is  placed  a  small  glass  funnel. 
After  complete  solution  (except  the  SnO2),  transfer  con- 
tents to  a  porcelain  dish,  evaporate  to  dryness,  moisten 
with  HNO3,  add  H2O,  and  filter  from  the  SnO2.  Dry  this 
residue,  ignite  in  porcelain,  and  weigh.  Fres.,  §  126,  I.,  a, 
and  §  91. 

B.—  Determination  of  Lead- 
To  filtrate  from  A  add  dilute  H2SO4,  evaporate  until 
fumes  of  H2SO4  appear,  or  the  residue  is  nearly  dry,  let 
the  dish  cool,  then  add  water,  and  filter  from  the  PbSO4. 
See  Fres.,  §  163,  2,  and  §  116,  3,  a,  p.  Dry,  ignite,  and 
weigh  precipitate.  See  Fres.,  §  83,  d. 

C.  —  Determination  of  Copper. 

The  filtrate  from  B.  should  not  measure  more  than  100 
c.c.  Place  the  solution  in  a  large  platinum  dish,  arrange 
the  Bunsen  cells  of  a  galvanic  battery,  connect  the  zinc 


36  QUANTITATIVE    ANALYSIS. 

element  with  the  platinum  dish,  and  the  carbon  element 
with  a  small  piece  of  platinum  foil  which  is  immersed  in 
the  liquid.  Let  the  battery  run  four  or  five  hours.  Take 
out  a  drop  of  the  solution  with  a  pipette,  place  on  a  watch 
glass  and  test  for  Cu  with  H2S.  Pour  out  the  solution 
when  the  precipitation  is  completed,  and  wash  thrice  with 
small  quantities  of  water.  Then  wash  the  copper  film 
with  alcohol  twice,  dry  in  the  hand,  over  a  Bunsen  burner, 
at  a  very  gentle  heat,  and  weigh  quickly. 

N.B.  —  It  is  advisable  to  test  solution  for  Cu  before 
proceeding  further. 

D.  —  Determination  of  Zinc. 

Heat  the  filtrate  and  washings  from  C  to  boiling,  add 
excess  of  Na2CO3,  boil  a  few  minutes,  wash  by  decantation 
hot,  then  on  filter,  Dry,  ignite,  and  weigh  as  ZnO.  Fres., 
§  108,  I,  a,  and  §  77. 


Analysis  No.  9.  —  COAL.     (PROXIMATE  ANALYSIS.) 

To  be  determined,  Moisture,  Volatile  and  Combustible 
Matter,  Fixed  Carbon,  Sulphur,  and  Ash. 

A-  —  Determination  of  Moisture. 

Pulverize  the  coal  very  finely,  heat  one  to  two  grms.  in  a 
half  ounce  platinum  crucible  for  fifteen  minutes  at  115°  C. 
in  an  air-bath,  cool  and  weigh.  Repeat  this  desiccation  in 
the  air-bath,  weighing  at  intervals  of  ten  minutes,  until  the 
weight  is  constant  or  begins  to  rise.  Loss  of  weight  gives 
moisture.  In  reporting,  give  exact  temperature  at  which 
it  was  determined.  N.B.  —  The  increase  in  weight  is  due 
to  oxidation  of  the  coal ;  it  generally  begins  after  heating 


ANALYSIS   OF    COAL.  37 

thirty  to  ninety  minutes  in  the  air-bath.  Anthracite  coal 
may  be  heated  an  hour  or  more.  See  Chem.  News,  Am. 
Repr.,  Vol.  V.,  p.  80. 

B.  —  Determination  of  Volatile  Combustible  Matter. 

Heat  the  same  crucible  with  contents,  closely  covered, 
to  bright  redness  over  a  Bunsen  burner,  exactly  three  and 
one-half  minutes,  and  then  without  allowing  the  crucible 
to  cool,  heat  strongly  before  the  blast-lamp,  exactly  three 
and  one-half  minutes  more.  Cool  and  weigh.  The  loss 
gives  the  volatile  and  combustible  matter,  and  includes  half 
the  S  in  the  FeS2.  See  F  below. 

C.  — Determination  of  Fixed  Carbon. 

Heat  crucible  and  contents,  uncovered,  over  Bunsen 
burner,  until  all  carbon  is  burned  off  and  the  weight  is 
constant.  This  takes  from  one  to  four  hours  or  more. 
Loss  in  weight  =  fixed  carbon,  including  half  the  S. 

D- —  Determination  of  the  Ash. 

The  difference  between  the  weight  last  obtained  and  that 
of  the  crucible  gives  the  weight  of  the  ash.  Note  color  of 
the  ash. 

B.— Determination  of  Sulphur. 

Secure  a  sample  of  anhydrous  Na2CO3,  shown  to  be  ab- 
solutely free  from  S  by  the  silver  test. 

Weigh  out  about  two  grms.  coal  in  fine  powder,  mix 
with  about  ten  grms.  NaNO3  and  ten  grms.  Na2CO3  on 
glazed  paper.  The  sodium  salts  need  not  be  weighed  ac- 
curately ;  KNO3  may  be  used  in  place  of  NaNO3.  Deflag- 
rate in  a  covered  two-ounce  platinum  crucible,  heating  over 


38  QUANTITATIVE    ANALYSIS. 

a  Bunsen  burner ;  add  the  mixed  coal  and  sodium  carbonate 
little  by  little,  replacing  the  cover  of  the  crucible  quickly 
each  time.  Do  not  expect  to  effect  a  perfect  fusion.  Place 
the  crucible  and  contents  in  a  casserole,  add  water,  and 
digest  until  the  mass  is  disintegrated,  and  the  crucible  can 
be  removed.  Add  cautiously  an  excess  of  HC1,  heat  to 
boiling,  and  throw  down  the  H2SO4  with  BaCl2  as  usual. 
If  flocks  of  SiO2  remain  insoluble  in  HC1,  evaporate  to 
dryness  on  water-bath,  heat  until  HC1  is  expelled,  add 
water,  filter,  and  proceed  as  above.  If  the  BaSO4  is  red- 
dish after  ignition,  wash  with  solution  NH4C2H3O2  and 
then  with  pure  water,  dry,  ignite,  and  weigh  again.  The 
BaSO4  may  also  be  purified  by  solution  in  cone.  H,SO4  and 
reprecipitation  with  water. 

Second  Method  for  Determining  Sulphur.  —  Put  two  to 
five  grms.  powdered  coal  in  a  flask  holding  a  litre ;  add 
100  c.c.  HNO3  and  five  grms.  powdered  KC1O3,  heat  to 
boiling,  adding  more  reagents  as  needed ;  continue  until  all 
the  carbon  is  oxidised.  Transfer  to  a  dish,  evaporate  to 
dryness,  add  HC1  and  water,  throw  down  H2SO4  with 
BaCl2,  and  proceed  as  usual.  Consult  Hayes's  article  in 
Am.  Chem.,  Feb.,  1875,  also  Wittstein's  article  in  Am. 
Chem.,  April,  1876. 

P.  —  Calculations. 

Theoretically  we  should  deduct  half  S  from  the  volatile 
combustible  matter  (because  iron  pyrites  loses  one-half  its 
sulphur  at  a  red  heat),  one-eighth  S  from  the  fixed  car- 
bon, and  three-eighths  from  the  ash.  (2FeS  become  Fe2O3, 
or  8  X  4==  32  reduces  to  8  X  3  —  24.) 

Practically  half  the  amount  of  sulphur  is  deducted  from 
the  volatile  combustible,  and  half  from  the  fixed  carbon ; 
reports  should  be  made  out  accordingly. 


ANALYSIS    OF    COPPER    PYRITES.  39 

G-, —  Estimation  of  Carbon  and  Hydrogen. 

Ignite  one  grm.  of  coal  with  PbCrO4  in  a  hard  glass 
tube  0.25  metre  long.  Pass  the  H2O,  CO2  and  H2SO4 
formed  through  two  U-tubes,  one  containing  ignited  CaCl2, 
and  the  other  a  solution  of  Pb(NO3)2,  and  through  a  potash 
bulb.  The  increase  in  weight  of  the  first  U-tube  gives  the 
H2O,  and  that  of  the  potash  bulb  the  CO2. 

Calculation  of  Calorific  Power.  —  One  part  of  carbon  in 
burning  yields  8,080  calorific  units,  and  one  part  of  hydrogen 
in  burning  34,460  calorific  units.  Hence  to  calculate  total 
calorific  units  in  a  coal,  multiply  the  percentage  of  C  by 
8,080  and  divide  by  100;  also  multiply  the  percentage  of 
H  by  34,460  and  divide  by  100.  Add  the  quotients. 

(A  calorific  unit  is  the  amount  of  heat  necessary  to  raise 
one  grm.  of  water  from  o°  to  i°  C.)  See  Chem.  News, 
XXXIV,  p.  233.  1876. 

Analysis  No.  10.  —  COPPER  PYRITES. 
Determination  of  Copper. 

Pulverize  very  finely.  Weigh  out  exactly  2  grms.,  place 
it  in  a  flask  of  about  300  c.c.  capacity  and  covered  with  a 
small  funnel,  the  stem  of  which  is  slipped  into  the  neck  of 
the  flask.  Add  20  c.c.  cone.  HNO3,  5  c.c.  cone.  HC1,  mix- 
ing these  in  flask  under  the  hood.  Digest  some  minutes, 
then  add  cautiously  20  c.c.  cone.  H2SO4  and  boil  hard  un- 
til fumes  of  H2SO4  appear  abundantly.  Cool,  add  water 
with  caution,  dilute  not  too  largely,  filter  from  residue  (SiO2, 
CaSO4,  etc.),  and  wash.  Test  residue  for  copper  before 
the  blow-pipe.  Dilute  filtrate  to  200  c.c.  exactly,  mix  well 
by  pouring  into  a  dry  beaker  and  back  again  three  or  four 
times  ;  divide  in  halves  by  taking  out  100  c.c.  with  a  pipette 


4O  QUANTITATIVE    ANALYSIS. 

and  place  in  a  platinum  dish  previously  weighed.  (N.B. — 
Volumetric  apparatus  as  sold  is  rarely  reliable,  therefore 
test  pipette  and  flask  before  measuring  as  above.)  Arrange 
two  cells  of  a  Bunsen  battery,  placing  the  "  battery  acid  " 
(one  part  of  H2SO4  diluted  with  8  to  10  of  water)  in  the 
outer  cell  and  "battery  fluid"  (K2Cr2O7+H2SO4+H2O)  in 
the  inner.  Connect  the  zinc  (-(-)  pole  with  the  platinum 
dish,  and  the  carbon  ( — )  pole  with  a  piece  of  platinum 
foil  which  is  immersed  in  the  liquid.  Cover  the  platinum 
dish  with  two  pieces  of  glass  plate,  one  each  side  of  the 
platinum  foil,  to  prevent  loss  by  spattering.  Or  use  the 
cone  or  spiral  described  in  Chem.  News,  XIX,  p.  222  (1869). 
See  also  Crookes  Select  Methods,  pages  187-200. 

It  is  best  not  to  let  the  battery  run  all  night ;  prepare 
the  solutions  on  one  day  and  start  the  battery  the  next 
morning.  Four  hours  or  more  usually  suffice  for  complete 
precipitation. 

Test  a  few  drops  of  the  solution  with  H2S. 

When  precipitation  is  complete,  pour  off  liquid,  wash 
copper  with  distilled  water  three  or  four  times  (work  rap- 
idly), then  with  strongest  alcohol  twice ;  drain  the  alcohol 
off,  dry  the  copper  at  a  very  low  heat,  holding  the  plati- 
num dish  in  the  hand  over  a  small  flame,  which  must  not 
touch  the  dish,  and  weigh  immediately.  Next  treat  the 
remaining  100  c.c.  solution  likewise ;  the  two  determina- 
tions should  agree  to  about  0.2  per  cent. 


Analyses  No.   11  and  No.   12. 
Introductory  Note  3  on  Volumetric  Analysis. 

Definition.  "  Volumetric  Analysis  is  a  form  of  quantita- 
tive analysis  in  which  we  seek  to  estimate  the  amount  of 
a  substance  from  the  determinate  action  of  reagents  in 


VOLUMETRIC    ANALYSIS.  41 

solutions  of  known  strength,  the  amount  of  the  reacting 
substance  being  calculated  from  the  volume  of  the  liquid 
used."  The  first  principles  and  method  of  procedure  have 
been  foreshadowed  in  Analysis  No.  3,  III.,  Determination 
of  Iron  by  Marguerite's  method.  For  explanation  of  gen- 
eral volumetric  methods,  see  Fres.  §  54,  and  consult  Sut- 
ton  s  Handbook  of  Volumetric  Analysis,  also  Mohr's  Lehr- 
bnch  der  cJiemisck-analytisdien  Titrirmethode. 

Principles.  When  volumetric  analysis  first  came  into 
use,  the  standard  solutions  were  so  prepared  as  to  give 
results  in  percentages  ;  thus  in  Alkalimetry,  one  standard 
solution  of  acid  was  used  for  potash,  another  for  soda,  etc. 
The  modern  system  is  based  on  the  fact  that  acids  and 
alkalies  (as  well  as  other  reagents)  neutralize  each  other  in 
the  proportion  of  their  molecular  weights,  or  of  simple 
multiples  of  the  same  ;  consequently  standard  solutions  are 
so  prepared  that  one  litre  contains  one-half  or  the  whole 
of  the  molecular  weight  of  the  reagent  weighed  in  grms. 
For  example,  the  molecular  weight  of  HC1  being  36.5  and 
that  of  KHO  56.1,  36.5  grms.  of  HC1  exactly  neutralize 
56.1  grms.  of  KHO,  and  if  these  respective  amounts  be 
dissolved  in  one  litre  of  water,  the  whole  of  one  solution 
will  not  only  neutralize  the  whole  of  the  other,  but  any 
aliquot  part  of  one  will  exactly  neutralize  a  similar  aliquot 
part  of  the  other.  And  by  using  graduated  vessels,  (bu- 
rettes,) the  amount  of  reagent  used  is  determined  by  the 
volume  of  the  solution.  (Before  employing  burettes, 
pipettes,  and  graduated  flasks,  care  should  be  taken  to  test 
the  accuracy  of  the  graduation.) 

Standard  Solutions.  Solutions  containing  the  molecu- 
lar weight  of  the  reagent  expressed  in  grms.  per  litre  are 
called  normal  solutions  ;  in  the  case  of  di-basic  acids 
(H2SO4,  H2C2O4  etc.)  and  of "  di-acid  "  alkalies  (Na2CO.) 


42  QUANTITATIVE    ANALYSIS. 

one-half  the   molecular  weight  of  each  is    taken,    making 
half  normal  solutions. 

The  standard  solutions  of  the  following  reagents  are 
made  with  the  quantities  indicated  : 

Oxalic  acid  H2C2O4-f-2  aq.  63  grms.  per  litre 

Sulphuric  acid  H2SO4  49      "  " 

Hydrochloric  acid  HC1  36.5    " 

Sodium  carbonate  Na2CO3  53      "  " 

Potassium  hydrate  KHO  56.1    "  " 

Ammonia  NH3  17      " 

The  point  of  neutralization  or  end  reaction  is  determined 
by  adding  to  the  solutions  some  organic  coloring-matter 
which  changes  in  hue  under  the  influence  of  an  alkali  or 
an  acid.  The  "  indicators "  commonly  used  are  litmus 
solution  and  cochineal  solution. 


ALKALIMETRY. 
(Cf.  Sutton's  Handbook.) 

1.  Preparation   of   Litmus    Solution. — Digest    5    to   6 
grms.  litmus  with  about  200  c.  c.  water  for  half  an  hour  or 
more ;    decant  the  clear  liquid  or  filter ;    add  very  dilute 
HNO3  drop  by  drop,  until  the  color  is  changed  to  violet. 
If  properly  neutralized  less   than   one-tenth  c.c.  of  stand- 
ard acid  should   distinctly   redden   one  c.c.   litmus  in   100 
c.c.  of  water. 

2.  Sulphuric  Acid. —  Mix   about   60  grms.    cone.    C.P. 


ALKALIMETRY.  43 

H2SO4  of  sp.  gr.  1.840  with  three  or  four  times  its  volume 
of  distilled  water  ;  cool  and  dilute  to  one  litre.  The  ex- 
act standard  of  this  solution  is  determined  by  testing  with 
sodium  carbonate,  as  below. 

3.  Sodium  Carbonate  Solution.  —  Weigh  off  about  12 
grms.  anhydrous  C.P.  Na2CO3 ;  heat  in  a  porcelain  dish 
to  low  redness,  stirring  until  moisture  is  expelled ;  place  in 
a  desiccator  to  cool.  Weigh  out  accurately  10.6  grms.  of 
this,  and  dissolve  in  distilled  water.  Dilute  to  exactly  200 
c.c.  This  gives  a  half  normal  solution,  each  c.c.  of  which 
contains  0.053  grm.  of  sodium  carbonate,  as  shown  by  this 
simple  calculation : 

Na2  =  46 

C      =  12 

03       =  48 

Mol.  wt.  of  Na2CO3          106  ' 
One-half  the  mol.  wt.  =    53 

200  c.c.  :   i  c.c.  =   10.6  grms.:  0.053  grms. 
This  solution  serves  to  standardize  the  sulphuric  acid. 

Standardizing  the  Sulphuric  Acid. — Take  of  the  Na2CO3 
solution,  20,  30,  or  40  c.c.,  accurately  measured,  place  in  a 
wide-mouthed  flask  of  about  300  c.c.  capacity  ;  add  litmus 
solution,  and  run  in  H2SO4  solution  from  a  burette  until 
a  wine-red  color  is  obtained ;  boil  hard  to  expel  CO2,  and 
add  more  acid  until  the  color  is  permanent.  Read  off  the 
c.c.  used.  Repeat  the  process.  Suppose  30  c.c.  Na2CO3 
solution  required  25  c.c.  H2SO4  solution.  Then  5  c.c. 
(30  —  2  5)  water  must  be  added  to  every  25  c.c.  of  the  acid 
solution  to  make  it  normal.  •  Measure,  therefore,  the 
H2SO4  solution  carefully  and  add  the  necessary  amount  of 
water.  Suppose  the  H2SO4  solution  measures  900  c.c., 
since  900=25X36,  then  36  X  5,  or  180  c.c.  water  must 
be  added.  Add  the  water,  mix  well,  and  again  determine 


44  QUANTITATIVE    ANALYSIS. 

the  standard  :  one  c.c.  of  the  Na2  CO3  solution  should  ex- 
actly neutralize  one  c.c.  of  the  H2SO4  solution.  In  case  of 
difficulties  the  exact  standard  of  the  acid  should  be  deter- 
mined gravimetrically  by  precipitating  10  or  20  c.c.  with 
BaCl2,  and  calculating  from  the  BaSO4  obtained  the 
amount  of  H2SO4  in  one  c.c. 

Carminic  acid  being  stronger  than  carbonic  acid,  a  solu- 
tion of  cochineal  is  sometimes  substituted  for  litmus,  in 
which  case  boiling  may  be  dispensed  with.  The  dyestuff 
tropaeoline  has  recently  been  proposed  as  an  indicator  in 
alkalimetry.  Cf.  Ber.  d.  chem.  Ges.  XI,  460  (1878). 

Deci-normal  Solution  of  Acid. —  Call  the  above  normal 
solution  "No.  I  ;"  take  100  c.c.  of  No.  i,  put  into  a  litre 
flask,  and  dilute  to  one  litre.  Call  this  deci-normal  solution 

"  No.  2." 

A. — Valuation  of   Soda  Ash. 
(Determination  of   Na2CO3.) 

Place  about  12  grms.  powdered  sample  in  a  platinum 
crucible  or  porcelain  dish  ;  heat  moderately  for  some  min- 
utes over  a  Bunsen  burner,  until  all  moisture  is  expelled ; 
cool,  weigh  out  exactly  10  grm. ;  dissolve  in  water;  dilute 
to  one-half  litre  and  mix  well.  Take  out  50  c.c.  solution 
(which  contains  one  grm.  soda  ash),  and  determine  the 
amount  of  normal  acid  needed  to  neutralize,  adding  litmus 
as  before,  and  boiling  to  expel  CO2. 

Suppose  50  c.c.  solution  soda  ash  required  i  5  c.c.  stand- 
ard acid,  then  9-°53*g^*  I0°  =  79-5  per  cent.  Na2CO3. 
See  Fres.,  §  207,  p.  500.  These  results  are  only 
approximative  and  preliminary,  and  the  operation  must 
be  repeated,  finishing  with  the  deci-normal  solution  No. 
2,  as  below.  Take  another  50  c.c.  of  soda  ash  solution; 
run  from  a  burette  12  c.c.  of  solution  "  No.  i,"  and  then 


ACIDIMETRY.  45 

finish  with  solution  "  No  2."     Of  course,  in  calculating,  10 
c.c.  of  No.  2  equals  one  c.c.  of  "  No.  i." 

B.  — Valuation  of  Pearl  Ash. 

Proceed  as  before;  weigh  quickly  the  salt  cooled  in  a 
desiccator,  for  it  is  very  hydroscopic.  In  calculating,  use 
the  factor  0.0691. 

The  Residual  Method  of  Titration. —  This  method  has 
great  advantages  over  the  foregoing  method,  especially 
when  carbonates  are  in  question  ;  the  sharpness  of  the  end 
reaction  being  much  increased  by  the  absence  of  CO2. 
The  process  is  as  follows :  Super-saturate  the  soda  ash 
solution  with  normal  acid  in  excess ;  then  add  normal  pot- 
assic  hydrate  (and  decinormal  also)  until  the  neutral  point 
is  reached.  (The  normal  KHO  is  mentioned  in  the  next 
paragraph.)  Since  one  c.c.  acid=  one  c.c.  alkali,  substract 
the  number  of  c.c.  of  standard  alkali  from  the  number  c.c. 
of  standard  acid  added  in  the  first  place,  and  then  calculate 
as  usual. 

ACIDIMETRY. 

Generalities. — The  value  of  strong  acids,  especially  HC1, 
HNO3,  H2SO4,  is  frequently  deduced  from  the  Specific 
Gravity  as  determined  by  the  hydrometer.  See  tables  in 
Fres.,  pp.  488,  491,  showing  percentages  of  acids  in  solu- 
tions of  different  densities.  When  titration  is  desirable, 
standard  KHO  solution  is  used,  and  in  accordance  with 
the  principles  already  stated. 

Preparation  of  Standard  Alkali. — Take  about  60  grms. 
KHO,  dissolve  in  I  litre  of  water,  add  Ca(HO)2  to  throw 
clown  carbonates,  boil,  let  settle,  and  syphon  off.  Deter- 
mine the  exact  standard  of  this  with  normal  and  deci- 
normal acid. 


46  QUANTITATIVE    ANALYSIS. 


A.— Valuation  of  HC1. 

Take  5  to  50  c.c.  acid,  according  to  strength,  dilute  to  a 
definite  volume,  take  an  aliquot  part,  add  litmus  and  run  in 
the  standard  KHO  as  described. 

In  calculating  multiply  the  number  of  c.c.  of  KHO 
added  by  .0365  X  100,  and  divide  this  product  by  the  num- 
ber of  c.c.  of  acid  taken  X  Specific  Gravity  of  the  solution 
as  determined  by  the  hydrometer. 

Example. — Took  10  c.c.  HC1  solution,  having  a  Specific 
Gravity  =  1.025  ;  since  I  c.c.  of  water  weighs  I  grm.,  the 
weight  of  acid  taken  —  10.25  grms. 

The  acid  solution  required  8  c.c.   KHO,  whence 

8  X  .0365  X  ioo 

-  -  =  2-84  Per  cent. 


B.— Analysis  of  Vinegar. 

A.  Determine  the  acetic  acid  by  titration,  using  cochi- 
neal solution,  or  with  methylaniline  violet,  as  in  the  "  Witz 
method"   (Am.  C/iem.,Vo\.  VI,  page  12),  or  use  Mohrs 
method,  as  follows : 

Add  to  a  known  quantity  of  acid  a  weighed  quantity 
(in  excess)  of  pure  precipitated  dry  CaCO3.  After  de- 
composition is  nearly  complete  in  the  cold,  boil  to  expel 
CO2,  filter,  and  wash  the  excess  of  CaCO3  in  hot  water. 
Dissolve  the  CaCO3  in  excess  of  normal  HC1,  and  deter- 
mine the  HC1  remaining  by  means  of  normal  KHO,  or 
NaHO  and  litmus  solution.  The  results  with  dark 
colored  vinegars  are  good. 

B.  Determine  water  by  drying  at  100°  C.  to  constant 
weight,  and  allow  for  alcohol  and  acetic  acid. 


CHLORIMETRY.  47 

C.  Determine  alcohol  by  neutralizing   about    300   c.c. 
vinegar   with    CaCO3    and   distilling   off    some   measured 
amount,  say  150  c.c.     Then  determine  specific  gravity  by 
weighing,  and  from  this  calculate  the  per  cent,  of  alcohol. 

D.  Determine  the  grape  sugar.     (See  Analysis  No.  33.) 


Analysis  No.  13. — CHLORIMETRY. 

Constitution  of  Bleaching  Powder. 
Bleaching  powder  is  formed  thus  : 

2CaH2O2  +  2C12  =  2H2O  +  CaCl2O2,CaCl2. 

The  composition  of  bleaching  powder  is  variously  given. 
The  following  are  some  of  the  formulae. 

"  Quelques  Chimistes,"  CaCl2  +  H2O2.  . 
Watts,  CaCIO  +  CaCl,  Ca2O  +  2H2O. 
Bloxam,  CaO  C12O  +  CaCl2  2CaO  +4H2O. 
Roscoe,  CaCl2O2. 
Muspratt,  CaO  C12  2H2O. 
Fownes,  CaCl2  -f-  CaCl2O2. 
Calvert,  2CaCl2  +  CaCl2O2. 

Thorpe,  Ca3H6O6Cl4  =  CaCl2O2  +  CaH2O2+  CaCl2  + 
2H2O. 

Kolb,  (2CaO,Cl2H20),  CaH2O2. 

Rose,  (CaCl2,  Ca2O2)  CaO2Cl2  +  4H2O. 

Stahlschmidt's    theory   of    its   formation :      Bericht  D. 
CJtcm.  Ges.,  1875  : 

3CaH202  +  4C1  =  CaCl2  +  CaCl2O2  +  CaH2O2  +  2H2O. 

See  paper  on  Constitution  of  Bleaching  Powder,  by  Dr. 
Lunge  in  American  Chemist,  Vol.  V,  page  454. 


48  QUANTITATIVE    ANALYSIS. 

When  allowed  to  stand  in  contact  with  air  and  light,  it 
decomposes,  CaCL  increasing,  and  the  CaCIO  decreas- 
ing. Dry  chloride  of  lime,  at  50°  C.,  decomposes  thus : — 
(THORPE.) 

3Ca3H606Cl4  =  5CaCl2  +  Ca(ClO3)2  +  3CaH2O2  +  6H2O. 

By  the  action  of  water  chloride  of  lime  decomposes 
thus : 

Ca3H606Cl4=  CaH2Oa  +  CaCl2  +  CaCl2O2  +  2H2O. 

The  value  of  the  commercial  article  depends  wholly 
upon  the  amount  of  "  available  chlorine,"  viz. :  the  Cl  in 
the  hypochlorite,  which  is  thus  constantly  varying. 

The  strongest  contains  38.5  per  cent,  available  chlorine. 
One  or  two  per  cent,  of  this  is  present  as  calcium  chlorate, 
which  is  without  bleaching  power. 

Action  of  Acids  on  Bleaching  Powder.  —  Action  of  hy- 
drochloric acid : 

(CaQ202  +  CaCl2)  +  2HC1  =  2CaCl2  +  2(HC1O). 
Action  of  dilute  sulphuric  acid : 

(CaCl202  +  CaCl2)  +  H2SO4  =  CaSO4  +  CaCl2  + 
2(HC10). 

Further  action  of  concentrated  sulphuric  acid  : 

CaS04  +  CaCl2  +  2(HC1O)  +  H2SO4  ==  2(CaSO4)  + 
4C1  +  2H2O. 


CHLORIDE    OF    LIME.  49 


Valuation  of  Chloride  of  Lime. 

Penofs  Method.  From  Fresenius'  Quant.  Analysis, 
§212.  Based  on  the  conversion  of  an  alkaline  arsenite, 
into  an  arseniate  by  a  solution  of  chloride  of  lime. 

As2O3  +  CaCl2O2  —  As2O5  +  CaCl2. 

The  end  reaction  is  determined  by  KI  and  starch,  un- 
decomposed  hypochlorite  turning  this  mixture  blue. 

(a.)  Preparation  of  KI  Starch  Paper.  —  Boil  three  grms. 
starch,  in  250  c.c.  water,  add  one  grm.  KI,  one  grin. 
Na2CO3  +  aq. ;  dilute  to  500  c.c.  Moisten  paper  with 
this  solution  and  dry. 

(b.}  Preparation  of  Solution  of  As2Or —  Dissolve  ex- 
actly 4.95  grms.  pure  sublimed  As2O3  with  25  grms. 
Na2CO3  -\-  aq.  (free  from  S)  in  200  c.c.  water.  Boil  until 

N 
dissolved   and   dilute   to    one   litre.     Make  a  —  solution. 

Since  it  is  difficult  to  weigh  out  exactly  this  amount,  take 
any  number  and  dilute  proportionately.  If  5.013  grms., 
then 

4.95   :  i ooo  =  5.013  grms.  :   1012.7. 

Add  then  12.7  c.c.  to  the  litre.  One  c.c.  of  this  solu- 
tion =  0.00355  Cl. 

(c.)  Process  of  the  Determination.  —  Mix  sample  well ; 
weigh  out  10  grms.,  rub  in  mortar  with  50  or  60  c.c.  water ; 
settle;  decant  turbid  liquid  into  a  litre  flask.  Repeat. 
Fill  up  to  mark,  and  mix. 

Fill  a  burette,  take  50  c.c.,  run  it  into  a  beaker,  add  the 
standard  As2O3  solution,  stirring  until  a  drop  of  the  so- 


5O  QUANTITATIVE    ANALYSIS. 

lution  no  longer  gives  a  blue  mark  on  the  KI  starch  paper. 
Repeat  on  fresh  amount.  Caution :  Shake,  and  draw  off 
turbid  liquid. 

(d.)    Calculation. 

c.c.  As2O,  solution  used X 0.0035 5  X  100 

: =  per  cent.  Cl. 

Amount  taken 

[French  chlorimetrical  degrees  represent  the  number  of 
litres  of  Cl  at  o.°C.  and  760  m.m.,  which  one  kil.  of  sample 
should  yield.  Now  one  litre  of  Cl  weighs  3.177  grms. ; 
hence  31.77  per  cent.  =  100  degrees.  See  foot-note  on 
p.  505  of  Fres.  Quant.  Anal.'] 

The  amount  of  calcium  chloride  present  may  be  de- 
termined by  first  estimating  the  hypochlorite  as  above,  and 
then  adding  to  the  second  portion  of  50  c.c.  a  slight  excess 
of  NH4HO  and  warming. 

3  CaCl2O2  +  4  NH3  =  3CaCl2  +  6H2O  +  4N. 

Neutralize  the  solution  with  HNO3  and  determine  the 
Cl  by  AgN03. 

The  amount  of  chlorate  may  be  determined  by  heating 
a  third  portion  with  ammonia,  then  acidulation  with  pure 
H2SO4  and  digesting  with  Zn. 

Ca(C103)2  +  I2H  =  CaCl2  +  6H2O. 

Again  determine  the  Cl  by  AgNO3,  and  the  increased 
amount  over  the  second  determination  gives  the  Cl  exist- 
ing as  chlorate.  (THORPE.) 


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52  QUANTITATIVE   ANALYSIS. 

Note  I.  —  Some  of  the  tin  may  go  into  solution  as 
nitrate  of  tin,  if  the  nitric  acid  be  dilute,  and  thus  appear 
in  Precipitate  c  mixed  with  the  sulphide  of  antimony ;  in 
this  case  they  should  be  separated  by  F.  W.  Clarke's 
method,  which  is  based  on  the  solubility  of  the  sulphide 
of  tin  in  oxalic  acid,  and  details  of  which  may  be  found  in 
Crookes'  Select  Methods,  page  249.  For  another  method 
see  Fres.,  §  165,  4,  a,  also  §  165,  7,  a. 

Note  2.  —  On  the  other  hand,  some  of  the  antimony 
and  lead  may  refuse  to  dissolve  and  remain  with  Residue  a, 
in  which  case  proceed  as  follows :  after  igniting  and  weigh- 
ing the  SnO2  +  Pb  ?  +  Sb  ?  fuse  with  Na2CO3  and  sulphur 
in  a  porcelain  crucible.  Dissolve  in  warm  water  and  filter 
from  the  residue  of  PbS,  which  may  be  treated  with  HNO3 
in  a  porcelain  crucible  and  weighed  as  PbSO4.  To  the 
alkaline  solution  add  slight  excess  of  HC1  and  collect 
precipitate  of  SbS3  -f-  SnS2  +  S  on  filter ;  dry  and  remove 
excess  of  S  by  washing  with  CS2,  transfer  to  porcelain 
capsule,  oxidize  with  HNO3  evaporate  to  dryness,  fuse 
with  NaHO  in  a  silver  dish,  dissolve  the  mass  in  a  mixture 
of  three  volumes  of  alcohol  and  one  of  water,  and  filter 
from  the  antimoniate  of  sodium.  For  details,  see  Fres., 
§  165,  4,  a  To  the  solution  containing  stannate  of  sodium, 
add  HC1,  saturate  with  H2S,  and  treat  the  precipitated 
SnS2  as  usual.  See  Fres.,  §  126,  I,  c,  and  §  91. 

Consult  article  on  the  Estimation  of  Antimony,  by  E. 
H.  Bartley,  in  American  Chemist,  Vol.  V,  page  436;  also 
paper  by  Dr.   Clemens  Winkler,  in  Fresenius'  Zeitschrift 
fur  Analytische  Chemie,  Heft  2,  1875. 


DETERMINATION    OF    ZINC. 


53 


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$6  QUANTITATIVE    ANALYSIS. 

Analysis  No.   17.  —  PYROLUSITE. 
Determination  of  MnO2. 

Employ  Fresenius  and  Will's  method  as  described  in 
Fres.  Quant.  Analysis,  edition  of  1870,  pages  509-12, 
§  215,  A.  See  also  Mohr's  Titrirmethode  §  215,  pp.  617-638 
(ed.  1874). 

Take  3.955  grms.  of  ore,  and  use  Geissler's  carbonic 
acid  apparatus  if  available. 

Consult  also  the  following  article :  "  On  the  Estimation 
of  Peroxide  of  Manganese  in  Manganese  Ores,"  by  E. 
Scherer  and  G.  Rumpf,  Chemical  News,  American  Re- 
print, Vol.  VI,  page  82,  February,  1870. 


Analysis  No.   18.  —  FELDSPAR. 

A-  —  Determination  of  Alkalies. 

Prof.  J.  Lawrence  Smith's  method.  See  Am.  J.  Sci. 
[3]  I,  269.  Also  Fres.,  §  140,  II,  b,  r> 

Pulverize  well  in  an  agate  mortar.  Weigh  out  one  grm. 
of  the  silicate.  Mix  well  in  an  agate  mortar,  first,  with 
about  one  grm  of  NH4C1  (pure  enough  to  sublime  without 
residue),  and,  secondly,  with  about  eight  grms.  C.  P.  pre- 
cipitated CaCO3 ;  add  the  latter  in  three  or  four  portions, 
mixing  well  after  each  addition.  Transfer  the  mixture  by 
means  of  glazed  paper  to  a  platinum  crucible. 

Apply  the  heat  of  a  Bunsen  burner  to  the  upper  portion 
of  the  crucible  first  and  gradually  carry  the  flame  toward 
the  lower  part,  until  the  NH4C1  is  completely  decomposed, 


DETERMINATION    OF    ALKALIES. 


57 


which  ensues  in  four  or  five  minutes.  Then  heat  before 
the  blast-lamp,  not  too  intensely,  for  thirty  to  forty  min- 
utes. 

This  operation  is  greatly 
facilitated  by  using  a  special 
apparatus  devised  for  the  pur- 
pose by  Prof.  J.  Lawrence 
Smith,  and  represented  in 

Fig-  5- 

The  stand  H  supports  on 
its  rod  G  a  cast-iron  plate  B 
perforated  by  a  hole  large 
enough  to  admit  the  some- 
what elongated  crucible  A; 
the  bottom  of  the  crucible 
projects  within  the  sheet  iron 
chimney  C  which  is  held  in 
its  place  by  the  hook  N. 
When  heat  is  applied  to  the 
bottom  of  the  crucible  by  the 
flattened  burner  F  the  decom- 
position proceeds  regularly  and  is  completed  in  about  one 
hour. 

Cool  the  crucible,  place  it  in  a  porcelain  casserole,  and 
digest  the  semi-fused  mass  with  boiling  water  until  tho- 
roughly disintegrated.  This  may  take  some  hours.  Then 
filter  from  the  residue  (SiO2,  Fe2O3,  A12O3,  Mn2O3(?), 
CaO,  etc.),  and  wash  well  with  about  200  c.c.  of  water. 
All  the  alkalies  of  the  silicate  are  converted  into  chlorides 
and  are  now  in  the  water  solution.  Add  to  this  solution 
NH4HO  and  (NH4)aCO3  with  a  few  drops  of  (NH4)2C2O4. 
Evaporate  without  filtering,  on  a  water-bath,  to  about  50 
c.c.,  add  a  little  NH4HO,  and  filter  through  a  small  filter 
(No.  2)  into  a  weighed  platinum  dish.  Evaporate  to  dry- 


FIG  5. 


58  QUANTITATIVE     ANALYSIS. 

ness  on  a  water-bath,  ignite  very  gently  to  drive  off  a  little 
NH4C1,  and  weigh.  If  the  residue  is  not  perfectly  soluble 
in  water,  and  quite  white,  dissolve,  filter  off,  evaporate, 
ignite,  and  weigh  again.  This  gives  the  weight  of  the 
KC1  +  NaCl. 

Next  determine  the  K,  either  by  separating  it  with  PtCl4 
and  alcohol  in  the  usual  manner,  or  by  gravimetric  or  vol- 
umetric estimation  of  the  total  Cl  in  the  weighed  chlorides. 
For  calculation,  see  Fres.,  §  197,  a.  Consult  also  Crookes' 
Select  Methods,  pages  13  and  14. 

B.  —  Determination   of  SiO2,   A12O3,   Pe2O3,    CaO, 
and  MgO. 

Fuse  two  grms.  mineral  with  six  grms.  K2CO3  -f-  six 
grms.  Na2CO3.  Moisten  with  water,  digest,  add  excess  of 
HC1,  evaporate  to  dryness,  expel  HC1  in  air-bath,  add 
water  and  HC1,  and  filter  from  SiO2.  Continue  exactly  as 
in  Analysis  No.  7. 


SOLUBLE    SILICATES. 


59 


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6O  QUANTITATIVE    ANALYSIS. 


Analysis  No.   19.  —  IRON  SLAG. 

To   be   determined:      SiO2,    FeO,    MnO,    A12O3,    CaO, 
MgO,    S,    P205. 

Pulverize  finely;  weigh  out  exactly  five  grms. ;  mix 
on  glazed  paper,  by  means  of  a  horn  spatula,  with 
fifteen  grms.  anhydrous  Na2CO3  and  fifteen  grms.  K2CO3, 
together  with  one  grm.  NaNO3.  These  fluxes  need  not 
be  accurately  weighed.  Put  one-third  the  mixed  slag 
and  fluxes  into  a  two-ounce  platinum  crucible,  and  heat 
over  a  Bunsen  burner  until  by  settling  down  room  is 
made  for  more.  Heat  twenty  minutes  or  more  before 
the  blast-lamp.  Cool  suddenly,  place  in  a  casserole, 
and  treat  with  boiling  water  until  thoroughly  disinte- 
grated. Remove  the  crucible  and  add  excess  of  HC1 
little  by  little,  avoiding  loss  of  liquid  by  violent  efferves- 
cence;  evaporate  to  dryness  on  water-bath,  expel  HC1 
completely  by  drying  (not  above  1 15°  C.)  in  an  air-bath. 

Moisten  with  water,  add  HC1,  digest,  and  proceed  as  per 
scheme  on  following  page. 


IRON    SLAG. 


61 


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66  QUANTITATIVE   ANALYSIS. 


Notes  to  the  Preceding-  Scheme. 

Note  i.  SAMPLING  THE  ORE. — Break  up  in  an  iron  mortar 
forty  or  fifty  pounds  into  pieces  that  will  pass  through  a  tin 
sieve  with  half-inch  holes.  Thoroughly  mix  the  fine  and 
coarse.  Break  up  about  ten  pounds  of  average  quality,  so 
that  it  will  pass  through  a  tin  sieve  with  quarter-inch  holes. 
Mix  well,  take  one  pound,  and  pulverize  in  the  iron  mortar 
until  it  will  pass  through  a  brass  sieve  of  60  meshes  to  the 
linear  inch.  Mix  well,  take  out  about  50  grammes,  pul 
verize  in  agate  mortar,  pass  through  muslin  bolting  cloth, 
and  put  into  a  small  bottle,  tightly  corked,  for  analysis  and 
special  determinations.  It  is  yet  necessary  that  every 
portion  of  this  required  for  the  main  analysis  or  a  special 
determination  should  be  further  pulverized,  as  needed,  in 
an  agate  mortar,  to  an  impalpable  powder. 

Note  2.  PRELIMINARY  FUSION. — Thoroughly  mix  the  ore 
and  its  fluxes  on  glazed  paper,  put  about  a  third  of  the 
mixture  in  a  two-ounce  platinum  crucible,  the  lower  portion 
of  whose  interior  surface  has  been  previously  lined  with  a 
thin  layer  of  Na2CO3,  and  heat  over  a  common  Bunsen 
burner  with  strong  flame  until  the  greatest  violence  of  the 
effervescence  has  ceased.  Then  add  and  treat  the  two- 
thirds  remaining  successively  and  with  the  same  precaution. 
Finally,  heat  strongly  over  the  blast-lamp  until  the  mass  is 
in  complete  and  quiet  fusion,  adding  a  little  more  Na2CO3, 
should  it  not  readily  fuse.  The  time  required  for  this 
fusion  varies  fron  30  to  50  minutes. 

Certain  highly  aluminiferous  ores  obstinately  resist  this 
method  of  attack ;  in  such  cases  mix  with  the  flux  a  known 
weight  (two  or  three  grammes)  of  chemically  pure  precipi- 
tated silica  which  has  been  strongly  ignited  just  before 
weighing.  The  amount  of  silica  added  is  afterwards 
deducted  from  the  total  amount  found  in  Residue  d. 


NOTES  TO  THE  PRECEDING  SCHEME.          6/ 

Note  3.  REMOVAL  OF  THE  FUSED  MASS. — Let  the  crucible, 
cool  until  just  below  red  heat,  then  chill  it  suddenly  by 
plunging  it  into  cold  water  contained  in  a  porcelain  cas- 
serole, lay  the  crucible  on  its  side  and  digest  with  boiling 
water.  The  fused  mass  will  generally  become  detached 
from  the  crucible  and  come  out  in  a  cake.  Then  remove 
the  crucible,  wash  it,  treat  in  a  small  beaker  with  a  little 
cone.  HC1  to  remove  any  adhering  particles  of  the  mass, 
and  add  this  solution  to  that  of  the  INSOLUBLE  RESIDUE 
(2).  Should  any  portion  of  the  fused  mass,  thicker  than  a 
film,  obstinately  resist  solution  in  the  hot  water,  it  ought  to 
be  removed  only  by  patience  and  long  boiling ;  and  no 
attempt  should  be  made  either  to  dig  it  out  or  to  dissolve 
it  in  HC1;  lest  by  the  formation  of  Aqua  Regia  or  free  Cl 
(in  the  presence  of  NaNO3>  or  Mn2O3)  the  crucible  be 
attacked  and  injured. 

Note  5.  SEPARATION  OF  SiO2. — In  order  to  render  the 
SiO2  entirely  insoluble,  it  must  be  perfectly  dehydrated. 
The  evaporation  should  be  carried  to  dryness,  the  residue 
heated  until  odors  of  HC1  can  no  longer  be  detected,  and 
the  mass  is  hard  and  crumbly.  Since  the  residue  is  to  be 
re-fused  with  Residue  b,  the  drying  may  be  completed,  at  a 
temperature  somewhat  higher  than  100°  C.,  in  an  air-bath. 

Note  8.  PRECIPITATION  OF  BaSO4. — Avoid  the  addition 
of  a  large  excess  of  BaCl2  solution.  Add  only  5  c.c.  at  first, 
and  then  after  complete  subsidence  of  precipitate,  add  a 
few  drops  to  determine  if  any  H2SO4  remains  unprecipi- 
tated,  etc.  Then  proceed  as  in  Fres.,  §  132,  I,  i.  After 
decanting  the  clear  supernatant  liquid,  boil  the  precipitate 
with  water,  allow  to  subside,  decant,  filter,  and  wash  with 
hot  water.  These  precautions  are  necessary  to  dissolve 
out  any  other  salts  of  barium,  which  are  always  carried 
down  on  the  first  precipitation.  If  the  precipitate  of  BaSO4 
is  dark  colored  after  ignition,  dissolve  in  the  crucible  in 


68  QUANTITATIVE    ANALYSIS. 

Jiot  cone.  H2SO4,  pour  into  cold  water,  and  collect  the  pre- 
cipitate as  before. 

Note  9.  SEPARATION  OF  SiO2. — Evaporate  as  in  Note  5. 
Then  add  HC1  quite  freely  and  warm  for  some  time  before 
adding  any  water,  as  the  high  heat  may  have  produced 
anhydrous  Fe2O3,  forming  an  oxychloride  which  is  very 
slow  to  dissolve,  especially  in  dilute  acid.  Should  the  acid 
already  added  be  too  dilute,  .concentrate  by  evaporation, 
add  cone.  HC1,  and  digest  at  a  moderate  heat. 

Note  ii.  PRECIPITATION  OF  THE  BASIC  ACETATES. — Fil- 
trate  f  combined  with  Solutions  ct  and  dv  must  be  very 
carefully  neutralized  with  sodium  carbonate.  (If  ammonium 
carbonate  were  used,  bromide  of  nitrogen  might  form  in 
Filtrate  g.)  To  neutralize  the  greater  portion  of  the  acid 
use  crystallized  sodium  carbonate,  and  complete  the  neu- 
tralization with  a  very  dilute  solution  of  the  carbonate,  add- 
ing it  drop  by  drop,  agitating  to  dissolve  the  precipitate, 
until  the  liquid  assumes  a  deep  mahogany-red  color.  If  a 
permanent  precipitate  forms,  add  a  little  hydrochloric  acid, 
and  repeat  as  above.  Then  dilute  the  solution  to  about  i 
litre  for  each  gramme  of  the  sesquioxide  present,  add  about 
20  grammes  sodium  acetate  dissolved  in  a  small  quantity  of 
water,  and  heat  the  whole  to  boiling. 

It  is  sufficient  to  boil  from  ten  to  fifteen  minutes  for  the 
complete  precipitation  of  the  acetates.  The  filtering  should 
be  done  rapidly  on  a  ribbed  filter,  keeping  the  fluid  hot,  and 
disturbing  the  settled  precipitate  as  little  as  possible. 
When  available  the  Bunsen  pump  may  here  be  used  with 
advantage.  After  the  supernatant  fluid  has  been  poured 
through  the  filter,  throw  on  the  precipitate  and  wash  it  with 
boiling  water  containing  a  little  sodium  acetate.  Should 
any  basic  acetate  separate  upon  concentrating  the  filtrate, 
add  some  sodium  acetate,  boil,  filter,  dissolve  the  precip- 
itate in  HC1,  and  unite  to  the  solution  cf  the  main  body. 


NOTES  TO  THE  PRECEDING  SCHEME.         69 

In  boiling  Filtrate  e  with  KC1O3  to  oxidize  FeO,  be 
careful  to  decompose  the  whole  of  the  chlorate  by  heat- 
ing with  excess  of  HC1. 

Note  1 2.  DETERMINATION  OF  P2O5. — To  remove  the  HC1 
in  Solution  g1  add  NH4HO  in  large  excess,  wash  the  pre- 
cipitates of  ferric  hydrate  and  ferric  phosphate  by  decanta- 
tion  two  or  three  times,  and  redissolve  in  hot  cone.  HNO3. 
Evaporate  this  solution  down  to  small  bulk  (i5oc.c.  to  100 
c.c.),  partially  neutralize  with  NH4HO,  and  add  about  50 
c.c.  of  solution  of  ammonium  molybdate  in  nitric  acid.  If 
the  solution  is  very  acid,  ammonium  nitrate  is  formed  by 
the  partial  neutralization  as  above,  otherwise  add  a  small 
quantity  of  the  salt.  Warm  the  solution,  do  not  boil,  and 
let  stand  24  hours  or  more.  Then  filter  from  the  yellow 
granular  precipitate  of  ammonium  phospho-molybdate  with- 
out bringing  it  all  on  the  filter,  and  wash  the  precipitate 
with  a  solution  prepared  by  mixing  100  parts  of  the  precipi- 
tant with  20  parts  of  HNO3  (sp.  gr.=  i.2)  and  80  parts  of 
water.  Dissolve  the  yellow  precipitate  by  pouring  a  small 
quantity  of  dilute  NH4HO  through  the  filter  into  the 
original  beaker,  and  determine  the  phosphoric  acid  in  the 
ammoniacal  solution  by  means  of  magnesia  mixture  (5  c.c.) 
in  the  usual  manner.  Magnesia  mixture  is  preferably  made 
with  magnesium  chloride.  If  the  crystalline  ammonio- 
magnesium  phosphate  falls  mixed  with  flocculent  magne- 
sium hydrate,  add  HC1  until  dissolved  and  reprecipitate 
with  NH4HO. 

Reserve  the  filtrate  and  washings  of  the  yellow  precipi- 
tate, and  test  for  phosphoric  acid  by  adding  a  little  more 
of  the  ammonium  molybdate  solution,  heating  and  allowing 
to  stand  12  hours.  If  a  yellow  precipitate  forms,  pour 
through  a  separate  filter,  dissolve  in  dilute  NH4HO  and 
add  to  the  ammoniacal  solution. 

If   the   yellow  precipitate  first  obtained   was   not   suf- 


7O  QUANTITATIVE    ANALYSIS. 

ficiently  washed,  a  red  residue  of  oxide  of  iron  may  remain 
on  the  filter,  in  which  case  pour  dilute  HNO3  upon  it, 
allow  it  to  pass  into  the  ammoniacal  solution,  acidulate 
that  with  HNO3,  warm,  add  more  of  the  precipitant,  and 
set  aside  as  before;  filter  and  wash  several  times  with  the 
diluted  precipitant,  then  dissolve  the  precipitate  on  the 
filter  and  that  adhering  to  the  beaker  in  as  little  dilute 
NH4HO  as  possible. 

The  yellow  granular  precipitate  of  ammonium  phospho- 
molybdate  is  not  sufficiently  constant  in  composition  to 
admit  of  directly  weighing  it  in  exact  analysis ;  it  is  there- 
fore dissolved  in  NH4HO  and  the  phosphoric  acid  thrown 
down  with  magnesia  mixture  as  just  detailed.  According 
to  Nuntzinger's  analysis,  after  drying  at  100°  C.,  it  contains 

3-577  Per  cent-  NH4HO 
3.962        "         P205 
92.461         "         MoO3 

100.000 

Lipowitz  says  the  precipitate  dried  at  20°  to  30°  C.  con- 
tains 3.607  per  cent,  of  P2O5,  and  Eggertz  3.7  to  3.8  per 
cent.  P2OS.  When  dried  at  120°  C.,  Sonnenschein  found 
about  3  per  cent.  For  properties  of  this  precipitate  see 
also  Fres.,  §  93,  i,  foot-ncte.  Consult  also  Finkener's 
paper  in  Bericht  d.  d.  chem.  Ges  XI,  p.  1638  (1878),  and 
Chem.  News,  XXXVIII,  p.  63,  (1878). 

Note  13.  WASHING  OF  FE2O33H2O. — Wash  this  precipi- 
tate by  boiling  up  with  water  and  decanting  until  the  wash 
water  shows  very  little  alkaline  reaction  with  litmus  paper, 
and  gives  very  little  precipitate  with  solution  of  AgNO3. 
Then  transfer  to  filter,  and  wash  thoroughly  with  boiling 
water. 

Note  1 6.  DETERMINATION  OF  MN. — (Gibbs'  process,  Am. 


NOTES  TO  THE  PRECEDING  SCHEME.         /I 

your.  Sci.  [2]  XLIV,  p.  216.)  To  the  HC1  solution  add 
NH4HO  in  excess  and  solution  of  Na2HPO4  in  large 
excess.  Then  add  dilute  H2SO4  or  HC1  until  the  white 
precipitate  redissolves,  heat  to  boiling,  and  add  NH4HO  in 
excess.  Digest  near  the  boiling  point  about  an  hour,  when 
the  precipitate,  at  first  white  and  gelatinous,  becomes 
rose-colored  and  forms  crystalline  scales.  Filter  and  wash 
with  hot  water.  If  tinged  red,  redissolve  the  precipitate  in 
dilute  HC1,  and  repeat  the  process.  On  ignition  the  pre- 
cipitate is  converted  into  Mn2P2O7,  a  nearly  white  powder. 

If  Zn  is  present,  it  must  first  be  separated  as  in 
SCHEME  I,  Am.  Chem.,  Vol.  I,  p.  323. 

Note  1 8.  VOLUMETRIC  DETERMINATION  OF  FE. — Put 
Solution  kl,  which  must  be  completely  free  from  the  KC1O3 
used  to  oxidize  Filtrate  k,  into  a  wide-mouthed  reduction 
bottle  holding  about  250  c.  c.  Carefully  let  down  into  the 
bottle  a  lump  of  amalgamated  zinc,  free  from  iron,  and  a 
strip  of  platinum  foil  resting  upon  it,  add  about  10  c.  c. 
cone.  H2SO4,  cover  with  a  watch-glass  and  set  aside  over 
night.  To  ascertain  if  the  reduction  is  complete  test  the 
solution  with  ammonium  sulpho-cyanide,  which  should 
give  only  a  trace  of  pink  color. 

Then  introduce  into  a  flask  holding  about  200  c.  c.,  and 
fitted  with  a  Kronig  valve,  exactly  0.2  gramme  iron  piano- 
forte wire,  add  dilute  H2SO4,  and  heat  until  complete 
solution  of  iron.  Cool  the  flask,  pour  and  wash  out  the 
contents  of  the  flask  into  a  large  beaker  containing  about 
400  c.  c.  cold  water,  add  a  little  concentrated  H2SO4  and 
titrate  with  a  solution  of  K2Mn2O8  (13  grms.  in  2  litres 
water)  to  determine  its  strength.  Repeat,  and  average 

results. 

Now  pour  and  wash  out  the  contents  of  the  reduction- 
bottle  into  a  large  beaker,  add  cone.  H2SO4,  and  titrate 
with  the  standard  K2Mn2O8  as  before.  If  the  HC1  was  not 


72  QUANTITATIVE    ANALYSIS. 

properly  removed  from  Solution  fa  the  dark  brown-red 
ferric  chloride  formed  will  interfere  with  the  end  reaction 
of  the  permanganate.  In  such  a  case  reprecipitate  with 
NH4HO,  wash  thoroughly,  and  proceed  as  with  Solution  k*. 

Treat  Solution  &  in  exactly  the  same  manner,  and  aver- 
age the  results.  Cf.  Analysis  No.  3,  C.  III. 

For  method  of  repeating  the  titration  in  the  same  solu- 
tion, see  Crookes'  Select  Methods,  p.  74. 

SUNDRY  SUGGESTIONS. —  i.  Solution  a*  may  be  used  for 
duplicating  the  determination  of  S,  provided  the  absence 
of  Fe  is  proved  by  the  proper  tests.  Duplicate  determina- 
tions of  Ca  and  Mg  can  be  made,  if  desired,  in  the  filtrate 
from  the  precipitate  formed  by  ammonium  hydrate  in 
Solution  bz,  provided  this  precipitate  be  thoroughly  washed. 

2.  Duplicate  determinations  of   Ti  and  of    Fe  can  be 
made  in  Solution  bl\  the  Fe  can  also  be  estimated  volu- 
metrically  by  dissolving   in  acid  the  weighed  precipitate 
resulting  from  the  treatment  of  Solution  g2.     In  the  latter 
case,  however,  the  presence  of  TiO2  will  impair  the  results. 

3.  The  purity  of  the  SiO2  obtained  in  Residue  d  may  be 
tested,  after  weighing,  by  heating  with  fluoride  of  ammon- 
ium and  concentrated  sulphuric  acid  in  a  platinum  crucible, 
whereby  all  the  SiO2  is  expelled  and  is  determined  by  the 
loss  in  weight,  the  residue  being  TiO2  probably  colored  by 
Fe. 

4.  In  fusing  Residue  c  or  Precipitate  k,  hydro-sodium 
sulphate  may  be  substituted  for  KHSO4,  but  since  the  for- 
mer contains  water  of  crystallization  it  should  be  heated 
until  the  water  is  expelled  before  using  in  fusions.      In 
either  case  avoid  expelling  the  whole  of  the  H2SO4,  or  if 
the  mass  is  heated  to  redness,  partially  cool,  add  cone. 
H2SO4  and   heat  again  at  a  lower  temperature.     In  this 


NOTES  TO  THE  PRECEDING  SCHEME.          73 

way  the  TiO2  will  be  held  in  solution  by  the  excess  of  acid, 
and  the  resulting  acid  sulphate  will  dissolve  out  readily. 

For  Special  Determinations  see  NOTES  TO  SCHEME  I  in 
American  Chemist,  Vol.  I,  pp.  323  et  seq. 

REACTIONS. — A  full  discussion  of  the  many  and  complex 
reactions  which  take  place  in  the  preceding  scheme  for  the 
analysis  of  iron  ores  is  superfluous. 

We  add  a  few  remarks  and  equations  which  may  serve 
to  throw  light  upon  some  points. 

A. — The  action  of  potassium  permanganate  on  ferrous 
sulphate  has  already  been  formulated  in  connection  with 
the  notes  to  Analysis  No.  3.  This  action,  however,  may  be 
regarded  as  taking  place  in  two  stages,  as  follows : 

ist  stage.     2KMnO4+H2SO4=K2SO4+2HMnO4. 
2d  stage.     2HMnO4+7H2SO4+ioFeSO4=2MnSO4. 

+5(Fe2(S04)3)+8H20. 

Solution  bz  is  treated  with  excess  of  NH4HO  and  the 
precipitate  dissolved  in  H2SO4  in  order  to  remove  the 
larger  part  of  the  HC1  which  might  vitiate  the  results  of 
the  titration  as  indicated  in  Note  18.  The  presence  of  HC1 
is  injurious  also  because  it  exerts  a  reducing  action  on  the 
permanganate  as  shown  in  the  equations  following : 

2HMnO4+i4HCl=2MnCla+8H2O+ioCl, 
and       2FeSO4+H2SO4+2Cl=Fe2(SO4)3+2HCl. 

B. — When  KC1O3  is  employed  in  acid  solution  as  an 
oxidizing  agent  (as  in  the  case  of  Filtrate  e),  the  reaction 
which  takes  place  depends  upon  the  acid  used  and  partly 
upon  the  strength  of  said  acid.  Concentrated  sulphuric 
acid  is  said  to  act  thus : 

6KC1O3+3H2SO4^2HC1O4+2C12O4+3K2SO4+2H2O 
and  nitric  acid  thus : 


74  QUANTITATIVE     ANALYSIS. 

8KC1O3  +  6HNO3  =  2KC1O4  +  6KNO3  +  6C1  +  130 

+  3H20. 

The  action  of  hydrochloric  acid  on  potassium  chlorate  is 
variously  formulated ;  Bottger  gives  the  equation  (i)  and 
Odling  (2): 

(1)  2KC1O3+6HC1=2KC1+C12O3+4C1+3H2O. 

(2)  4KC1O3+I2HC1=4KC1+3C1O2+9C1+6H2O. 

In  any  of  these  cases  the  powerful  oxidizing  agency  of 
KC1O3  is  evident. 


Appendix  to   Analysis   No.    21. 
A. — Method  for  the  Estimation  of  Fe  and  Ti  only. 

Sample,  pulverize,  fuse  i  grm.  ore  with  3  grms.  NaFl-(-i2 
grms.  KHSO4.  Dissolve  in  large  quantity  of  cold  water; 
if  there  is  any  considerable  residue  re-fuse.  Neutralize 
with  Na2CO3  until  a  slight  precipitate  forms,  then  add 
H2SO4  until  the  ppt.  redissolves  and  the  liquid  is  slightly 
acid.  Saturate  with  H2S  gas,  boil  some  hours,  occa- 
sionally adding  H2S  water.  Filter  from  the  precipitate 
of  TiO2-f-S,  dry,  ignite,  and  weigh,  if  dark  colored  re- 
fuse, etc.  To  filtrate  add  a  little  KC1O3,  boil  to  oxidize 
H2S.  Reduce  the  iron  with  amalgamated  zinc  and  plat- 
inum foil,  and  titrate  with  K2Mn2O8  as  usual.  As  a  result 
of  the  fusion  we  have 

4NaFl+SiO2+4H2SO4=4NaHSO4+SiFl4+2H2O. 


FLIGHT'S   METHOD. 


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76 


QUANTITATIVE   ANALYSIS. 


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NOTES  TO  THE  PRECEDING  SCHEME.          77 

Note  i. — Care  must  be  taken  in  dissolving  the  pig-iron  in 
HC1-|-KC1O3  not  to  add  the  oxidizing  agent  all  at  once,  nor 
too  rapidly,  otherwise  some  of  the  iron  may  remain  unoxi- 
dized.  Should  a  small  portion  of  ferrous  chloride  remain 
in  the  solution,  the  subsequent  precipitation  of  the  iron  as 
basic  acetate  (as  in  Filtrate  f,  Analysis  No.  21)  will  be 
imperfect ;  instead  of  an  orange  red  flocculent  precipitate 
resembling  ferric  hydrate,  the  iron  will  fall  as  a  brick-red 
pulverulent  precipitate,  (anhydrous  ferric  oxide  ?)  which 
has  the  property  of  running  through  niters. 

Note  2. — SiO2  obtained  in  this  manner,  and  dried  at 
100°  C.,  contains  6  per  cent.  H2O,  which  is  expelled  on 
ignition,  and  must  be  deducted  from  graphite  after  the 
SiO2  has  been  determined.  According  to  Allen  (see 
Chemical  News,  Vol.  XXIX.,  p.  91,  Feb.,  1874)  the  Si  of 
the  pig-iron  is  converted  by  the  action  of  dilute  HC1  into 
leucone,  3SiO.2H2O.  By  fusing  the  mixture  of  leucone  and 
graphite  with  KHO,  the  former  goes  into  solution,  and  both 
may  be  estimated  directly. 


AA.— Determination  of  Graphite  and  Silicon. 

Second  Method.  (EGGERTZ,  Ckem.  News,  XVI 1 1.,  p. 
232. — Mix  10  c.c.  H2SO4  with  50  c.c.  H2O,  cool,  add  5 
grms.  fine  borings,  boil  half  an  hour,  evaporate  one-third 
and  cool.  The  reaction  is  as  follows  : 

2Fe4C+8H2SO4:=8FeSO4+C2H4+HI2. 

This  equation,  however,  but  imperfectly  formulates  the 
reaction,  the  S  forming  H2S  and  the  P  forming  PH3.  A 
large  number  of  compounds  of  C  and  H  are  evolved  in 
addition  to  the  C2H4  of  the  equation ;  according  to  Dr. 


78  QUANTITATIVE    ANALYSIS. 

Hahn  (Annalen  der  Chemie  und  Parmacie,  Vol.  129,  p.  57, 
1864)  they  include  the  following  : 


Gaseous.  • 


Ethjlene.  C2H4. 
Propjlene,  C~H6. 
Butylene,  C4H8. 


Liquid. 


( Amylene,      CKHin. 
Liquid.    {  _    J 

I  Caproylene,  C6H12. 


(Enanthene,  C7HM 
Caprylene,  C8Hlf 
Elaene,  C9H 

Paramylene,  C10H20. 
Cetylene,       ClfiH32. 
etc.  etc. 


18- 


Next  add  10  c.  c.  HNO3  and  boil  15  minutes. 

6FeS04+8HN03=2(Fe2(S04)3)+Fe2(N03)6+N202 

+4H20. 

Evaporate  on  a  water-bath  until  vapor  ceases  to  come  off 
and  the  mass  is  nearly  dry. 

Add  75  c.  c.  H2O+i3  c.  c.  HC1  and  boil  15  minutes; 
add  more  HC1  if  any  Fe2O3  remains  undissolved.  Filter 
through  a  filter  washed  with  HC1,  dried  and  weighed;  wash 
first  with  cold  water  until  no  more  iron  appears  in  wash- 
ings, then  with  boiling  water  containing  5  per  cent.  HNO3. 
Dry  at  100°  C.,  and  weigh  the  residue  consisting  of  SiO2+ 
graphite.  Ignite  and  weigh  again;  the  loss  in  weight  gives 
the  amount  of  graphite.  Lest  the  residue  contain  some- 
thing besides  SiO2  it  is  well  to  determine  the  latter  by 
heating  with  NH4F1  and  H2SO4,  which  expels  the  SiO2  in 
accordance  with  the  following  equation  : 

4NH4Fl+Si02+2H2S04=SiFl4+2(NH4)2S04+2H20. 

The  loss  in  weight  gives  the  amount  of  SiO2 ;  consult, 
however,  Note  2  of  A. 

AAA.— Graphite  determination  according  to  F.  A.  CAIRNS. 

Dissolve  5  grms.  borings  in  dilute  HC1,  boil,  filter,  wash 
with  hot  water,  then  with  KHO  solution,  then  with  boiling 


DETERMINATION  OF  TOTAL  CARBON.          79 

water,  then  with  («)  alcohol,  ($)  ether  and  (<:)  hot  water. 
Dry  and  transfer  to  flask  and  determine  as  in  B. 

In  this  process  the  combined  carbon  goes  off  in  volatile 
hydrocarbons,  and  graphite  -)-SiO2  together  with  certain 
liquid  hydrocarbons,  remain.  The  SiO2  is  removed  by  the 
KHO,  the  hydrocarbons  dissolve  out  in  the  alcohol  and  the 
ether,  while  the  latter  is  removed  at  last  by  boiling  water. 


B.— Determination  of  Total  Carbon. 

A.  H.  ELLIOTT'S  modification  of  ROGER'S  Process.  See 
Journal  of  Chemical  Society,  London,  May,  1869;  also 
CAIRNS'  article  in  Am.  Ckem.,  Vol.  II,  p.  140. 

To  2.5  grms.  of  borings  add  50  c.c.  of  a  neutral  solution 
of  CuSO4,  containing  one  part  of  sulphate  to  5  parts  of 
water;  heat  gently  for  10  minutes;  the  iron  dissolves; 
copper  is  precipitated,  and  the  silica,  graphite,  and  com- 
bined carbon  remain : 

Fe+CuS04=Cu+FeS04. 

The  cupric  sulphate  should  be  as  neutral  as  possible,  in 
order  to  avoid  loss  of  combined  carbon,  in  the  form  of 
volatile  hydrocarbons,  as  shown  in  AA. 

Add  20  c.c.  CuCl2  (i  part  of  chloride  to  2  parts  of  water), 
with  50  c.c.  strong  HC1,  and  heat  for  some  time  nearly  to 
boiling,  until  the  copper  dissolves : 

CuCl2-f-Cu=:Cu2Cl2. 

Prepare  an  asbcstus  filter  as  follows  :  select  a  glass  tube 
of  about  3  to  4  cm.  diameter,  and  18  to  20  cm.  in  length. 
Draw  out  this  tube  to  taper  at  one  end,  and  place  broken 
glass  and  asbestus,  lightly  packed,  in  the  narrowed  portion 
of  the  tube.  (See  Fres.,  §  229,  I,  a,  Fig.  100.)  Filter  the 
cuprous  solution  through  the  asbestus,  wash  thoroughly 


8O  QUANTITATIVE    ANALYSIS. 

with  boiling  water,  and  transfer  contents  of  filter  to  a  flask 
holding  about  200  c.c.  In  making  this  transfer,  the  carbon, 
asbestus,  and  broken  glass  may  be  blown  into  the  flask 
together,  in  order  to  use  as  little  water  as  possible.  Add 
to  the  contents  of  the  flask  about  3  grms.  of  CrO3,  (or  if 
this  is  not  available,  about  5  grms.  K2Cr2O7),  and  arrange 
apparatus  as  in  the  determination  of  CO2  by  direct  weight, 
Analysis  No.  7,  note  8,  II  (page  34).  Avoid  adding  more 
water  than  absolutely  necessary  to  transfer  the  carbon. 
'Add  30  c.c.  to  40  c.c.  concentrated  H2SO4,  little  by  little, 
shaking  constantly,  and  closing  cock  of  funnel-tube  each 
time.  Finally,  heat  gently  to  boiling,  not  allowing  more 
than  three  bubbles  of  CO2  gas  to  pass  per  second : 

3C+4Cr03+6H2S04^3C02+2Cr2(S04)3+6H20. 

Boil  one  minute,  attach  guard  tube  of  soda  lime,  and 
aspirate  slowly,  three  bubbles  per  second.  Weigh  the 
soda-lime  tube  for  amount  of  CO2  absorbed,  and  calculate 
the  amount  of  carbon. 

Note — The  carbon  separated  from  cast-iron  by  treatment 
with  sulphate  of  copper  contains  H  and  O,  and  cannot 
therefore  be  determined  by  weighing  directly.  'Schutzen- 
berger  and  Bourgeois  assign  to  it  the  composition  expressed 
by  the  formula  Cir3H2O,  and  consider  it  related  to  graphitic 
acid.  Bulletin  de  la  Societe  Chimique  de  Paris,  Vol.  23, 
No.  9. 

BB.— Other  Methods  for  determining  Total  Carbon. 

A  great  number  of  methods  have  been  devised  for  deter- 
mining total  carbon,  some  of  which  we  will  briefly  outline, 
remarking,  however,  that  the  foregoing  is  entirely  satis- 
factory. 


DETERMINATION  OF  TOTAL  CARBON.          8 1 

1.  Method  of  ALVARGONZALEZ.     See  Am.  Chem.,  Vol.  V., 
p.  437. — Place  10  grms.  of  borings  in  a  beaker  and  treat 
with  a  solution  of  cupric  sulphate  (40  grms.  CuSO4  in  200 
200  c.c.  H2O),  stirring  until  the  reaction  ceases.     Add  di- 
lute HNO3  gradually,  and  let  stand  until  the  copper  has  dis- 
solved.    Dilute  the  solution  and  filter  through  one  of  Roth- 
ers  half  filters  (described  in  Chem.  News,  Jan.  30,   1874, 
p.    57),  wash  thoroughly,  and   dry  on  funnel  at  100°  C. 
Detach  ppt.  from  filter  carefully,  place  in  a  weighed  cru- 
cible (throw  away  filter),  dry  at  100°  C.,  and  weigh.    Ignite  * 
and  weigh  again ;  the  difference  between  two  weighings 
gives  total  carbon. 

This  method  is  not  free  from  objections,  but  will  answer 
when  great  accuracy  is  not  indispensable,  and  speedy  results 
are  desirable. 

2.  Method  employed  by  I.  LOWTHIAN  BELL.    See  Chemical 
Phenomena  of  Iron  Smelting,  London,  1872. — Digest  3  grms. 
borings  from  24  to  48  hours  with  a  solution  of  CuSO4  in 
excess,  collect  the  spongy  Cu-|-C -(-graphite  on  an  asbestos 
filter,  and  burn  the  carbon  in  a  stream  of  oxygen  gas,  as  in 
the  ultimate  analysis  of  organic  bodies  collecting  the  CO2 
in  KHO  solution.     Cf.  Analysis  No.  30. 

3.  Method  of  REGNAULT  and  BROMEIS.     See  Crookes' 
Select -Methods,  p.  74. — Heat  borings  in  a  combustion  tube 
with  a  mixture  of  plumbic  chromate  and  KC1O3,  collecting 
the  CO2  in  KHO. 

4.  Methods  for  the  liberation  of  Combined  Carbon  are  also 
numerous. 

(a)  BOUSSINGAULT  triturates  the  iron  in  a  porcelain  mor- 
tar with  15  to  20  parts  of  HgCl2  and  sufficient  water  to 
make  a  thin  paste : 

Fe+2HgCl2=FeCl2+Hg2Cla. 


82  QUANTITATIVE    ANALYSIS. 

Then  dilute  with  200-250  c.c.  HC1  and  warm  for  an  hour; 
filter  from  the  SiO2-j-C,  wash  and  dry.  Transfer  to  a 
platinum  boat,  and  heat  in  a  current  of  pure  H,  volatilizing 
the  Hg2Cl2.  Weigh  the  C,  heat  again  in  a  current  of  O, 
burning  off  the  C,  and  weigh  again. 

(b)  WEYL  dissolves  the  pig-iron  under  the  influence  of 
a  galvanic  current.     Attach  a  weighed  piece  of  cast-iron  to 
the  positive  pole  of  a  Bunsen  cell,  and  suspend  it  in  dilute 
HC1.     The  iron  dissolves,  H  being  given  off  at  the  negative 
pole,  and  the  carbon  is  separated. 

Weyl  has  also  devised  another  method  based  upon  the 
following  reaction : 

Fe2+K2Cr207+7(H2S04)-Fe2(S04)3+Cr2(S04)3 
+;H20+K2S04. 

See  Crookes'  Select  Methods,  p.  76. 

(c)  MCCREATH'S  Method.    See  Engineering  and  Mining 
Journal,  March  17,  1877.    The  author  uses  double  chloride 
of  ammonium  and  copper  to  dissolve  out  the  iron,  while  the 
precipitated   copper  dissolves  in  excess  of  this  reagent; 
he  then  oxidizes  the  carbon  by  means  of  CrO3  in  an  appar- 
atus somewhat  similar  to  Elliott's,  collecting  the  CO2  in  a 
Liebig  potash-bulb. 

5.  EGGERTZ  Colorimetric  Method.  See  Crookes'  Select 
Methods,  pp.  81  to  84;  also  Britton's  paper  in  Journal  of 
the  Franklin  Institute,  May,  1870. 


C.  — Other  Methods  for  the  Determination  of  Sulphur 
and  Phosphorus. 

i.  EGGERTZ'S  Method.     See  Chem.   News,   Vol.   XVII, 
p.  207. 


DETERMINATION    OF    SULPHUR,    ETC.  83 

A.  Dissolve  10  grms.  KC1O3  in  200  c.c.  H2O,  place  in  a 
500  c.c.  flask,  add  5  grms.  fine  borings,  boil  and  add  60  c.c. 
HC1,  little  by  little,  boiling  until  the  Fe  dissolves : 

4KClO3+i2HCh=4KCl+3ClO2+9Cl+6H2O, 
and 

2Fe+C10a+Cl+4HCl=FeaCl6+2HaO. 

Evaporate,  dry  on  water-bath  to  insure  oxidation  of  sul- 
phur. Thorough  dryness  is  unnecessary,  since  SiO2  does 
not  interfere  in  acid  solution  with  the  precipitation  of 
BaSO4.  Then  add  10  c.c.  HC1-|-3O  c.c.  H2O,  and  digest 
on  water-bath  until  all  the  Fe2Cl6  is  dissolved.  Then  add 
20  c.c.  H2O,  filter,  and  wash  thoroughly.  Add  2  c.c.  of  a 
saturated  solution  of  BaCl2  (enough  to  precipitate  the 
H2SO4  from  o.i  grm.  S);  after  cooling  add  5  c.c.  NH4HO, 
stir  and  let  stand  24  hours.  Filter,  and  wash  by  decanta- 
tion  with  cold  water  two  or  three  times,  and  then  tho- 
roughly with  hot  water.  Dry,  ignite,  and  weigh.  If  the 
precipitate  shows  traces  of  iron  after  ignition,  purify  by  so- 
lution in  H2SO4. 

B.  For   the  determination   of   phosphorus  dissolve  the 
pig-iron  in  the  same  manner,  and  dry  at   140°  C  ;    some 
anhydrous  Fe2O3  will  remain  with  the  SiO2 ;    add  water, 
filter,  fuse  residue  with  a  little  KHSO4,  soften  with  H2SO4, 
and  dissolve  in  water.     Filter  from  the  SiO2,  and  determine 
it  as  a  check  on  the  main  analysis.     Add  filtrate  to  main 
one,  and  determine  the  P2O5  by  means  of  ammonium  molyb- 
date,  as  in  Analysis  No.  21. 

2.  Method  of  DR.  T.  M.  DROWN.  See  Am.  C/tem.,  Vol. 
IV,  p.  423. 

Treat  5  grms.  of  borings  in  a  flask  with  HC1,  and  pass 
the  H2S  and  PH3  formed  through  a  series  of  three  bottles 
containing  a  solution  of  K2Mn2O8(i  grm.  to  200  c.c.  H2O). 
Avoid  a  very  rapid  evolution  of  the  gas ;  when  this  ceases. 


84  QUANTITATIVE   ANALYSIS. 

aspirate  for  some  time,  and  then  pour  the  contents  of  the 
bottle  into  a  beaker,  rinse  with  water,  and  add  sufficient 
HC1  to  decompose  the  K2Mn2O8.  Filter  the  colorless  so- 
lution, add  BaCl2,  to  throw  down  the  H2SO4,  and  proceed 
as  usual. 

3.  Method  employed  by  ].  LOWTHIAN  BELL. 

Dissolve  in  HC1  as  above,  and  pass  the  gases  through  a 
solution  of  potassic  plumbate  (lead  nitrate  super-saturated 
with  KHO).  Boil  half  an  hour,  or  until  the  evolution  of 
gas  has  ceased.  Wash  the  PbS  formed,  oxidize  it  with 
HNO3,  and  throw  down  the  S  as  BaSO4  by  means  of 
Ba(NO3)2.  Let  stand  24  hours,  collect  on  a  filter,  dry, 
ignite,  and  weigh.  This  method  is  said  to  give  higher 
percentages  of  S  than  that  of  Eggertz.  Compare  Fres., 
§  229,  2. 

4.  Method  of  ARTHUR   H.    ELLIOTT.   See  Am.    Chem., 
Vol.  I,  page  376. 

5.  Method  employed  by  KONINCK  and  DIETZ.     See  Prac- 
tical Manual  of  Chemical  Analysis  and  Assaying  applied 
to  Iron.     Translated  by  Robert    Mallet.     London,    1872. 

Dissolve  3  to  5  grms.  borings  in  HC1  in  a  flask  connected 
with  four  bottles,  the  first  a  condenser,  the  three  following 
containing  solution  of  AgNO3(i  part  of  nitrate  to  20  parts 
of  water).  Boil,  and  when  gas  ceases  to  evolve,  aspirate 
Pour  contents  of  flask  on  one  filter,  and  wash  the  Ag2S. 
Wash  out  the  flask  and  cleanse  the  ends  of  the  tubes  witn 
bromine  water,  and  expel  excess  of  Br  by  heat;  the  follow 
ing  reaction  ensues  : 

Ag2S+8Br+4H2O=H2SO4+2AgBr+6HBr. 

The  phosphide  is  also  converted  into  phosphoric  at-tr 
Filter  from  AgBr,  and  ppt.  H2SO4  with  BaCl2  as  U.MUU. 


DETERMINATION  OF  IRON  MANGANESE,  ETC.      85 

6.  Method  of  BOUSSINGAULT  for  determination  of  Phos- 
phorus.      See  Annales  de  Chimie   et  de  Physique,    June, 

1875,  and  abstract   in  American  Chemist,  Vol.  VI,  p.  275. 

7.  For  additional  methods  consult  also  papers  by  Alfred 
H.    Allen,    Chem.    News,    XXIX,    p.   91,    and    paper    by 
Hamilton,    Chem.    News,   Vol.    XXI,    p.    147.      Compare 
Crookes'  Select  Methods,  pp.  84-89. 


D.— Determination  of  Iron  Manganese,  etc. 

The  iron  may  be  determined  by  difference  or  by  Margue- 
rite's method,  in  which  case  dissolve  0.2  grms.  of  pig-iron 
in  H2SO4,  and  proceed  as  usual.  It  is  advisable  to  use  a 
rather  dilute  solution  of  K2Mn2O8  towards  the  close  of  the 
oxidation. 

For  the  determination  of  the  bases  of  Groups  II,  III, 
and  IV,  dissolve  10  or  20  grms  of  pig-iron  in  HC1,  remove 
the  SiO2  by  drying  thoroughly,  and  proceed  as  in  Analysis 
No.  21. 

The  manganese  may  be  thrown  down  in  the  filtrate,  from 
the  basic  acetate  of  iron  by  means  of  bromine,  or  in  the 
absence  of  calcium,  magnesium,  etc.,  by  hydrodisodic  phos- 
phate. See  Fres.,  §  109,  3,  also  §  229,  5.  For  other  methods 
of  estimating  manganese  see  articles  by  Samuel  Peters  in 
Chem.  News,  Vol.  XXXIII,  p.  35,  and  by  William  Gal- 
braith,  in  Chem.  News,  Vol,  XXXIII,  p.  47. 

See  also  paper  by  Charles  H.  Piesse  in  Chem.  News, 
Vol.  XXIX.,  pp.  57  and  no. 

For  testimony  as  to  the  condition  in  which  silicon  exists 
in  pig-iron,  see  paper  by  E.  H.  Morton,  Chem.  News, 
Vol.  XXIX.,  p.  107. 


86 


QUANTITATIVE    ANALYSIS. 


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88  QUANTITATIVE   ANALYSIS. 

Analysis  No.  25. — GUANO. 

Consult  Fres.,  Quant.  Analysis  §§  233,  235,  and  236; 
also  article  by  F.  A.  Cairns,  Am.  Chem.,  Vol.  I,  p.  82. 

To  be  determined:  SiO2,  CaO,  MgO,  Fe2O3,  P2O5,  SO3, 
H2O,  NH3,  total  N,  organic  and  volatile  matter. 

A.— Determination  of  Moisture. 

Heat  i  grm.  at  100°  C.  until  constant  weight  and  loss— 
H20[+(NH4)2C03]. 

In  cases  where  great  accuracy  is  required,  a  correction 
for  the  (NH4)2CO3  counted  as  water  must  here  be  made. 
Heat  the  substance  in  a  U  tube  in  a  water-bath  and  aspirate, 
collecting  the  (NH4)2CO3  in  normal  H2SO4.  Titrate  with 
KHO  as  usual.  Subtract  (NH4)2CO3  found  from  H2O 
[+(NH4)2CO3]  determined  by  heating  at  100°  C.  as  above. 
B.— Organic  and  Volatile  Matter. 

Determine  loss  by  ignition  in  open  crucible,  and  correct 
for  H20,  (C02)  and  (NH4)2CO3). 

C.— Ammonia. 

Use  Schldsings  method,  Fres.,  §  99,  3,  b.  Mix  the  guano 
with  milk  of  lime  and  place  under  bell-jar  over  a  dish  of 
normal  H2SO4.  A  large  surface  of  acid  in  proportion  to 
the  guano  solution  is  desirable.  Let  stand,  cold,  48  hours 
or  more,  and  titrate  with  normal  KHO  as  in  acidimetry. 
(Cf.  Analysis  No.  1 1.) 

D.— Total  Nitrogen. 

Use  Varrentrapp  and  Will's  Method,  as  detailed  in  Fres., 
§  185.  Heat  the  guano  in  a  combustion  tube  with  soda 
lime,  converting  it  into  NH3.  Absorb  the  NH3  in  a  stand- 
ard solution  of  H2SO4,  aspirate  and  disconnect  bulb.  Add 
litmus  and  titrate  with  standard  KHO. 

B.— Sulphuric  Acid. 

Dissolve  in  hot  HC1,  filter  and  precipitate  with  BaCl2,  or 
follow  the  Scheme  F. 


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QUANTITATIVE    ANALYSIS. 


Analysis  No.  26. —  SUPERPHOSPHATE  OF  LIME. 

To  be  determined:  Moisture,  reduced  (or  reverted) 
P2O5,  soluble  P2O5  and  available  P2OS. 

A. — Determination  of  Moisture. 
Dry  I  grm.  at  100°  and  weigh — loss  of  weigh  t^moisture. 

B.— Determination  of  Total  P2O5. 

Weigh  out  i  grm.  accurately,  mix  with  2  grm.  KNO3  and 
4  grms.  Na2CO3,  fuse  in  platinum  crucible,  dissolve  in 
HNO3,  evaporate  in  a  casserole  to  dryness  (to  dehydrate 
SiO2+aq.),  add  water  and  filter.  Wash  thoroughly  and 
dilute  filtrate  to  500  c.c. ;  take  50  c.c.  of  this  solution 
(n^o.i  grm.  of  superphosphate)  and  determine  P2OS  with 
(NH4)2  MoO4  as  usual.  Consult  Note  12,  Analysis  No.  21. 

C.— Determination  of  Insoluble  P2OS. 

Digest  i  grm.  with  about  400  c.c.  of  water  in  8  to  10 
different  portions  successively,  rubbing  the  superphosphate 
with  water  in  a  porcelain  mortar.  Filter  and  treat  residue 
(filter  included)  with  about  50  c.c.  solution  of  ammonium 
citrate  containing  30  grm.  of  salt  to  100  c.c.  of  water,  and 
carefully  neutralized  if  acid.  Digest  at  about  7o°C.  for  40 
minutes  or  longer,  filter  and  wash.  Dry  residue  and  fuse 
exactly  as  in  B.  Estimate  the  P2O5  in  same  manner  using 
100  c.c.  (=0.2  grm.  of  superphosphate)  of  the  solution 
(500  c.c.)  for  each  determination. 

D.— Determination  of  Reduced  and  Insoluble  P2OS. 

Leach  another  sample  (i  grm.)  with  water  as  in  C 
(omitting  the  use  of  ammonium  citrate),  dry  the  residue 
and  fuse  as  in  B.  Continue  as  in  B,  taking  150  c.c.  of  the 
solution  for  each  determination. 


POTABLE   WATER.  91 

B.— Calculation. 


The  reduced  P2OS  is  found  by  subtracting  the  P2O5  in 
C  from  that  in  D.  The  soluble  P2O5=B-D  and  the  avail- 
able P2OS=B-C. 

Note. — Reduced  or  reverted  P2O5  forms  thus : 
Ca3P2O8+CaH4P2O8=2Ca2H2P2O8. 
Consult  Bolleys  Handbuch,  pages  802-806. 

Analysis  No.  27. — POTABLE   WATER. 

To  be  determined:  K;  Na;  Mg;  Ca;  Cl;  SO3 ;  SiO2; 
organic  and  volatile  matter,  total 
solids ;  hardness  (soap  test)  ;  oxy- 
gen required  to  oxidize  organic  mat- 
ter (permanganate  test). 

Quantity  required,  three  to  four  gallons  ;  collect  in  clean 
demijohns. 

A-— Determination  of  Total  Solids  and  Loss  by  Ignition. 

Measure  out  250  c.c.  of  the  water,  evaporate  to  dryness 
on  a  water  bath,  in  a  weighed  platinum  dish  of  100  c.c.  ca- 
pacity. During  the  evaporation  cover  the  dish  with  a 
paper  screen.  Dry  in  an  air  bath  I2O°-I3O°  C.  and 
weigh.  Weight  of  residue  gives  "Total  Solids."  Ignite 
gently  over  a  Bunsen  burner,  moisten  with  a  solution  of 
CO2  in  distilled  H2O,  dry  on  water-bath,  heat  in  air-bath 
I2O°-I3O°  C.  as  before  and  weigh;  difference  between 
second  and  first  weights*  gives  organic  and  volatile  mat- 
ter, also  called  "  Loss  by  Ignition."  For  further  treatment 
of  residue  see  F.  Compare  Chapter  II  of  Wanklyn's 
"  Water  Analysis;'  3rd  edition,  1874. 


9?,  QUANTITATIVE    ANALYSIS. 

B.— Determination  of  SiO2,  Fe2O3,  A12O3,  CaO,  MgO. 

Evaporate  4  to  6  litres  of  water  (according  to  the 
proportion  of  total  solids)  to  small  bulk  in  porcelain 
dish.  Add  HC1,  transfer  to  platinum  dish,  washing  care- 
fully the  porcelain  dish,  evaporate  to  dryness,  filter  from 
SiO2  and  follow  scheme  for  Dolomite,  Analysis  No.  7. 

C.— Determination  of  H2SO4. 

Take  I  litre  (or  less)  of  the  water,  boil  down  to 
200  c.c.  with  a  few  drops  of  HC1,  and  determine  SO4 
as  BaSO4  in  the  usual  manner.  If  the  water  contains 
sufficient  H2SO4  (as  sulphates)  to  give  a  feeble  precip- 
itate with  BaCl2  before  concentration,  one-half  or  one- 
quarter  litre  will  suffice. 

D.— Determination  of  Cl. 

Test  the  water  with  AgNO3  for  Cl,  and  if  no  cloud 
is  formed  evaporate  i  litre  to  small  bulk ;  otherwise  25 
to  50  c.c.  suffice.  Add  a  slightly  acid  solution  of  AgNO3, 
and  proceed  as  usual. 

Second  method.  Determine  the  Cl  volumetrically  by 
a  standard  solution  of  AgNO3,  using  potassium  chromate 
as  an  indicator.  See  Fres.  §  141,!,  b,  «. 

B. — Determination  of  Na  and  K. 

Evaporate  6  litres  to  dryness  in  a  large  porcelain  dish, 
finishing  on  a  water  bath.  Boil  the  residue  with  dis- 
tilled water  several  times,  filter  into  a  platinum  dish 
and  wash.  Add  Ba(HO)2  to  filtrate.  Evaporate  to  dryness, 
heat  to  low  redness,  let  cool,  take  up  with  water,  add 
(NH4)2CO3  and  a  little  (NH4)C2O4,  wash  the  precipitate, 
filter,  add  HC1  to  filtrate,  evaporate  to  dryness,  ignite 
and  weigh.  Dissolve  in  water  and  if  not  clear,  filter, 
evaporate,  dry,  ignite  cautiously,  and  weigh  again.  This 


POTABLE    WATER.  93 

residue  of  NaCl-)-KCl  must  be  perfectly  white  and  sol- 
uble without  residue  in  water.  Determine  the  Cl  in  the 
weighed  NaCl-{-KCl  and  calculate  the  Na  and  K  as  in 
Fres.  §197,  a.  Compare  Wanklyn,  ^rd  edition,  page  63. 

F. — To  check  determination  of  Na  and.  K. 

Moisten  the  weighed  "Total  Solids"  of  A  with  dilute 
H2SO4,  dry  and  ignite  with  a  little  powdered  (NH4)2CO3 
to  constant  weight.  By  deducting  from  this  weight, 
calculated  fot  one  gallon,  the  combined  weights  of  SiO2, 
Fe2O3,  A12O3,  CaO,  MgO  (the  latter  four  reckoned  as  sul- 
phates), the  weights  of  Na2SO4  and  K2SO4  are  obtained. 

G.— Dr.  Clark's  Soap  Test. 

Consult  Button's  Volumetric  Analysis,  §83,10:  or  Wank- 
lyn's  Water  Analysis,  3rd  edition,  page  125. 

Principle. — Hard  water,  so  called,  destroys  much  soap 
before  a  lather  is  formed,  owing  to  the  formation  of  insol- 
uble salts,  viz. :  stearates,  palmitates,  and  oleates  of  cal- 
cium and  magnesium. 

Preparation  of  Soap  Solutions. — Dissolve  10  grms.  of 
good  white  Castile  soap  (which  should  contain  about 
12  per  cent,  of  water)  in  I  litre  of  alcohol  90  to  95 
per  cent.  Let  stand  and  siphon  off  from  the  residue. 
Label  this  solution  "No.  I."  Take  of  solution  No.  I, 
ico  c.c.;  of  56  per  cent,  alcohol,  65  c.c. ;  of  distilled  water, 
75  c.c.,  and  mix.  Label  this  soap  solution  "  No  2." 

Preparation  of  Standard  Calcium  Solution. — Dissolve 
i  grm.  of  precipitated  CaCO3  in  HC1,  evaporate  until 
neutral,  take  up  with  water  and  dilute  to  1000  c.c.  I  c.c. 
of  this  solution  contains  grm.  o.ooi  CaCO3. 

Standardization  of  Soap  Solution. — Fill  a  burette  with 
soap  solution  No.  2.  Place  10  c.c.  of  calcium  solution 


94  QUANTITATIVE   ANALYSIS. 

in  a  glass  stoppered  bottle.  Add  it  to  100  c.c.  of  distilled 
water,  run  in  soap  solution  from  the  burette  and  shake 
well,  and  continue  adding  soap  solution  until  a  lather 
is  formed  of  sufficient  consistence  to  remain  for  five 
minutes  on  the  surface  of  the  water.  Read  burette  and 
calculate.  Repeat. 

In  certain  cases  allowance  should  be  made  for  the 
amount  of  soap  solution  destroyed  by  water  itself ;  100 
c.c.  destroys  0.8  c.c.  soap  solution. 

Performance  of  Analysis. — Same  as  above.  Report  mil- 
ligrammes per  litre  and  grains  per  gallon  of  CaCO3. 

Example. — loc.c.  of  the  standard  solution  of  chloride  of 
calcium  required  23  c.c.  of  soap  solution — 

But  10  c.c.  of  CaCl2  solution  is  equivalent  to  .01  grm. 
of  CaCO3,  hence 


c.c.  used) 
23 


)  )       .01  ) 

[•  i  c.c.   [•  =  [. :  *  =  .00043  grms. 

)  J       grm.  CaCO3  ) 

And  if  100  c.c.  of  water  under  examination  require 
33  c.c.  of  CaCl2  solution,  we  have  33 X. 00043 X  IO  =  grms. 
per  litre  of  CaCO3.  This  gives  .1419;  and  .i4i9X.O583i8 
gives  grains  per  gallon.  For  the  factor  .058318  consult 
I,  Calculation  of  Results. 


H.  Permanganate  Test  for  Organic  Matter. 

Principle. — Permanganate  of  potassium  in  solution  oxi- 
dizes putrescible  organic  matter. 

Preparation  of  solution  of  permanganate.  —  Dissolve 
0.320  grms.  of  permanganate  in  I  litre  of  water.  Dis- 
solve 0.7875  pure  oxalic  acid  in  I  litre  of  water,  weighing 
very  accurately.  Of  this  solution  i  c.c.=o.oooi  grm.  oxy 


POTABLE    WATER.  95 

gen.  To  standardize  the  permanganate,  take  10  c.c.  of 
oxalic  acid  solution  ;  dilute  to  100  c.c.  with  distilled  water, 
add  5  c.c.  dilute  H2SO4,  heat  nearly  to  boiling  and  run  in 
from  a  burette  the  permanganate  solution.  10  c.c.  of 
oxalic  acid  will  require  12  to  15  c.c.  permanganate.  Cal- 
culate value  of  I  c.c.  of  latter  in  milligrammes  of  oxygen. 

Testing  water. — Take  100  c.c.  potable  water  add  H2SO4, 
add  standardized  permanganate,  little  by  little  in  the 
cold,  until  the  water  retains  a  pink  tinges  after  one-half 
hour's  standing.  Report  amount  of  oxygen  required  to 
oxidize  organic  matter. 

Example. — 10  c.c.  of  standard  solution  of  oxalic  acid 
required  14  c.c.  of  solution  of  K2Mn2O8  — 

But  10  c.c.  of  H2C2O4  solution  is  equivalent  to  o.ooi 
grms.  of  oxygen,  hence 

c.c.  used^l  ^1          I.  mgm.  1 

\  :  i.  c.c.  >=  >  :  a  =  .0713  mgms. 

14.       J  J          oxygen  J 

And  if  100  c.c.  of  water  under  examination  required 
0.8  c.c.  of  K2Mn2O8,  we  have  O.8X.O/I3X  10  =  mgms.  per 
litre  of  oxygen  required  to  oxidize  organic  matter.  This 
gives  .5704  milligrammes  and  . 5 704 X. 05 831 8  gives  grains 
of  oxygen  per  gallon.  See  I,  Calculation  of  Results. 

I.— Calculation  of  Results. 

To  convert  grms.  in  a  litre  \X\\JQ  grains  in  a  gallon,  multi- 
ply the  number  of  milligrammes  of  each  constituent  by 
0.058318;  or  use  Dr.  Waller's  Table,  published  in  Am. 
CJtcm.,  Vol.  V,  p.  278.  Report  results  in  two  ways :  the 
grains  per  gallon  of  uncombined  constituents,  viz.,  SiO2, 
Fe2O3,  A12O3,  CaO,  MgO,  Na2O,  K2O,  Cl,  SO3,  together 
with  "  Loss  by  Ignition  "  and  "  Total  Solids ; "  and  secondly 


96  QUANTITATIVE    ANALYSIS. 

report  the  grains  per  gallon  of  the  bases  combined  with 
acids  in  accordance  with  the  following  scheme. 

Combine       "        "  Na  as  Na2  SO4 

"       excess  of  Cl    "  Mg  C12 

"  SO4  "  Ca  SO4 

"  "       "  Mg  "  Mg  CO3 

"  "       "  Ca    "  Ca  CO3 

"  "       "  K     "  K2SO4 

"  K     "  K  Cl 

"  "       "  Cl     "  Na  Cl 

The  sum  of  the  combined  salts  -f-  "  Loss  by  Ignition  " 
should  equal  the  "  Total  Solids  "  very  nearly. 

Example,  showing  method  of  calculation. — A  sample  of 
potable  water  yielded  on  analysis  the  following  results  : 

Cl  .215    grains   per  gallon. 

Na  .291        "          "         " 

SO3  .340 

CaO  .804      "         "        " 

etc.  etc. 

Begin  by  calculating  the  amount  of  Na  required  to 
saturate  the  Cl  found,  thus  : 

(i)  I'd      :  Na  =   f     Amount     j       J    Amount  of  Na 

[of  Cl  found.}    :  {needed  for  the  Cl. 
_35-5  •  23   =     0.215  :     w 

w  =  0.139  grains, 
hence  0.215  -f-  0.139  =  0.354  grains  NaCl. 

But  the  water  contains  .291  grains  Na,  hence  we  have 
.291  —  .139  =  .152  grains  Na  left  over  to  combine  with 
S03. 


POTABLE    WATER.  97 

0.152  grains  Na  corresponds  however  to  0.204  grains 
Na2O  making  then  a  proportion  similar  to  (i)  we  have 

(2)  f  Na2O  :  SO3  =  f  Amount    1        f    Amount  of  SO3    1 

j   of  Na2O     -   :   j  needed 

[  remaining,  j        [     for  the  Na2O. 
62       :  80    =     0.204  :  x 

x  =  0.263  grains, 
hence  0.204  -f-  0.263  =  0.467  grains  Na2SO4. 

But  the  water  contains  0.340  grains  SO3  hence  we  have 
0.340  —  0.263  =  0.077  grains  SO3  left  over  to  combine 
with  CaO. 

Accordingly  we  have  the  proportion 

(3)  fSO3:CaO  =  f  Amount  of  SO3|    f   Amount  of  CaO    1 

{     remaining,     j  '  [needed  for  the  SO3.  j. 
1 80    :     56  =    0.077  :  y  \ 

y  =  0.0539  grains  CaO, 
hence  0.077  +  0.0539  =  0.130  grains  CaSO4. 

Proceeding  in  like  manner  the  CaO  remaining  is  regarded 
as  combined  with  CO2. 

0.804  — 0.0539  =  0.7501  grains  CaO  ;  and  since. 

(4)J         CaO          :          CaCO3  =  0.7501        :       z 

whence  z  =  1.34  grains  CaCO3.     j 

Collecting  the  results  of  the  calculation  we  have  (thus 
far)  the  following  figures  for  the  constituents  combined: 

NaCl      —  0.354  grains  per  gallon. 
Na2S04  =  0.467      " 
CaS04  =0.130      " 
CaC03  =      1-34      " 
etc.,  etc. 


98  QUANTITATIVE   ANALYSIS. 

The   following  will  serve  as  a  further  example    of   the 
manner  of  reporting  similar  analyses. 

ANALYSIS  OF  CROTON  WATER  BY  DR.  C.  F.  CHANDLER. 

Grains  per  gallon. 

Soda 0.326 

Potassa 0.097 

Lime 0.988 

Magnesia 0.524 

Chlorine 0.243 

Sulphuric  acid  .         .         .         .         .         .  0.322 

Silica 0.621 

Alumina  and  oxide  of  iron  trace 

Carbonic  acid  (calculated)         .         .         .  2.604 

Water  in  bicarbonates  (calculated)  .         .  0.532 

Organic  and  volatile  matter       .         .         .  0.670 


6.927 
Less  oxygen  equivalent  to  the  chlorine     .  .054 

Total       .         .         .         6.873 
These  acids  and  bases  are  probably  combined  as  follows 


Chloride  of  sodium    . 
Sulphate  of  potassa  . 
Sulphate  of  soda 
Sulphate  of  lime 
Bicarbonate  of  lime  .       .  . 
Bicarbonate  of  magnesia  . 
Silica         . 

Alumina  and  oxide  of  iron 
Organic  matter 


6.8/3 


SPECIFIC    GRAVITIES    OF    SOLIDS    AND    LIQUIDS.  99 

Analyses  No.  28  and  No.  29.  —  SPECIFIC   GRAVITIES   OF 
SOLIDS  AND  LIQUIDS. 

A— Sp.  gr.  of  a  solid  by  direct  weight. 
Weight  of  solid  in  the  air  =  w 
"        "      "      "   water   =  w1 
w 

Sp.  gr.  = 

w  —  w1 

B.— Sp.  gr.  of  a  solid  by  the  flask. 

Weight  of  solid  =  w 

"   flask  +  water  =  w1 

"       "      "      "       "      +  solid  =  w" 
w 

Sp.  gr.  = 

(w  -f-  w1)  —  w11 

C.— Sp.  gr.  of  a  body  soluble  in  water. 

Weight  of  body  in  air  —  w 
«      «       «    oil  _  w, 

Sp.  gr.  of  oil  =  a 

"     "     "  water  =  i 

The  liquid  displaced  being 
w  —  w1  —  w11 

then 

a:  i  =  w11 :  w1" 
w 

Sp.  gr.  = 

w111 

D.— Sp.  gr.  of  a  body  lighter  than  water  and  insoluble 
in  it,  e.g.,  Cork. 

Weight  of  cork  in  air  =  w 

"        "  lead    "    water  —  w1 

"        "     "     and  cork  in  water  =  w" 


IOO  QUANTITATIVE   ANALYSIS. 

W 


Q 

w/_ 

E.  —  Sp.  gr.  of  a  Body  lighter  than  Water  and  soluble  in  it. 

Weight  of  body  in  air  =  w 

"      "      "  naphtha    =  w' 

w  —  w'  =  w" 

Sp.  gr.  of  naphtha     =  A 
"     "     "    water         =  i 

A  :  w"=  i  :  w'" 

c  w 

SP-  Sr-  -  jnr 

P.  —  Determination  of  the  Proportion  of  two  Metals  in  an 

Alloy. 

Sp.  gr.  of  the  alloy  =  S 

Weight  of  the  alloy  =  A 

Sp.  gr.  of  one  of  the  metals  =  s' 
Sp.  gr.  of  the  second  metal  =  s" 
Weight  of  one  metal  =  w' 

Weight  of  the  second  metal  =  w" 


(s'—  s")S 

w"  =  A—  w' 

For  proofs  of  this  formula,  see  Galloways  First  Step  in 
Chemistry,  p.  74. 

G.  —  Sp.  gr.  of  a  liquid  by  the  flask. 

Weight  of  flask  =  F 

"         "      "  and  water        =  w 
"       "     "     liquid        =  w' 


ORGANIC    ANALYSIS.  IOI 


H.  —  Sp.  gr.  of  a  Liquid  by  weighing  a  Substance  in  it. 

Weight  of  substance  =  w 

"         "         "  in  liquid  =  w' 

Sp.  gr.  of  the  substance  —  A 

w  :  (w — w')  =  A  :  sp.  gr. 

or    Sp.  gr.  =  (w~w  ) — 
w 

Analysis  No.  30,  31,  and  32.     Organic  Analysis. 

INTRODUCTORY  NOTES.  The  analysis  of  organic  bodies 
comprises  two  branches  ;  PROXIMATE  ANALYSIS  which  deals 
with  the  separation  of  proximate  principles  of  organic  bodies 
without  altering  them,  and  ULTIMATE  ANALYSIS,  by  which 
the  nature  and  quantity  of  the  elements  composing  the 
organic  bodies  are  determined. 

No  systematic  course  of  proximate  analysis  is  possible 
in  the  present  state  of  the  science ;  animal  chemistry  is  in 
this  respect  more  advanced  than  vegetable  ;  for  a  course  of 
zoo-chemical  analysis  see  article  by  Gorup-Besanez  in  the 
Neues  Handworterbuch  der  Chemie,  I,  551,  and  compare 
Watt's  Dictionary,  I,  249.  See  also  Heintz  Lehrbuch  der 
Zoochemie  and  LeJimaris  Physiological  Chemistry.  For 
general  principles  of  proximate  organic  analysis,  consult 
Dr.  Albeit  B.  Prescotfs  "  Outlines  of  Proximate  Organic 
Analysis"  a  most  useful  manual,  and  the  only  one  of  its 
kind.  For  special  methods  of  analyzing  organic  bodies, 
especially  of  commercial  articles,  consult  "  Bolleys  Hand- 
buck  der  TechniscJi-cJiemischen  Untersuchungen"  of  which 
the  second  edition  by  Emil  Kopp  is  most  valuable. 


TO2  QUANTITATIVE    ANALYSIS. 

The  method  of  conducting  an  ultimate  analysis  is  suffi- 
ciently detailed  in  Fresenius*  System,  §  171-189,  yet  the 
following  summary  may  be  of  service  in  calling  attention 
to  the  chief  points. 

A.  Determination  of  C,  H,  and  O,  in  Sugar. 

Select  a  very  pure  well  crystallized  sample  of  sugar,  rock- 
candy  will  do,  but  small  crystals  from  a  vacuum  pan  are 
better.  Dry  at  100°  C,  in  powder. 

Provide  the  following  articles  :  — 

(1)  The  dried  substance  in  a  tared  watch  glass. 

(2)  Combustion  tube  of  hard  glass  drawn  out  as  shown 
in  Fres.  §  174,  cleaned  and  carefully  dried. 

(3)  Liebig  potash  bulb  filled  with  a  KHO  solution  of 
Sp.  gr.  1.27,  or  a  U-tube  filled  with  soda-lime. 

(4)  Chloride  of  Calcium  tube  ;  that  of  the  form  described 
by  Thorpe  in  his  Quant.  Chem.  Analysis  page  347,  fig.  80  is 
advantageous. 

(5)  Small  U-tube  containing  potash-pumice  in  one  limb 
and  CaCl2  in  the  other. 

(6)  Rubber  tubing. 

(7)  Fine  wire  for  binding  the  tubing. 

(8)  Good  corks,  free  from  holes,  rolled  and  pressed. 

(9)  Cupric  oxide,  granulated  preferred,  chemically  pure, 
freshly  ignited  to  remove  organic  matter  and  moisture,  and 
contained  in  a  corked  holder. 

(10)  A  platinum    boat  to  contain  the  substance,  or  if 
another  process  be  followed,  a  mixing  wire. 

(11)  Combustion  furnace. 

(12)  If  oxygen  is  to  be  employed,  a  cylinder  of  this  gas 
and  a  system  of  drying  U-tubes  must  be  provided. 


ORGANIC    ANALYSIS.  IO3 

(13)  Sundry  articles,  such  as  glazed  paper,  agate  mortar, 
towel,  asbestus,  a  ramrod  for  cleaning  combustion  tube.  etc. 

Process  of  the  Combustion. 

(a)  Weigh  the  substance  (sugar)  and  preserve  in  a  des- 
iccator until  ready  for  use  ;  weigh  also  the  KHO  bulb  to- 
gether with  the  U-tube  (5),  CaCl2  tube. 

(b)  Dry  the  combustion  tube  and  fill  with  cupric  oxide  ; 
the  substance  may  be  inserted  on  a  platinum  boat  if  the 
combustion  is  to  be  conducted  with  oxygen,  otherwise  it 
must  be    intimately  mixed  with  some   powdered  CuO   in 
the  agate  mortar  and  transferred  by  the  glazed  paper  to 
the  combustion  tube.    Stir  also  with  the  iron  mixer.  Avoid 
introducing  moisture. 

(c)  Connect  the  apparatus,  arranging  it  as  shown  in  the 
cut  on  page  433  of  FrescniuJ  System.     Test  the  joints  by 
heating  the  air  in  that  bulb  of  the  KHO  apparatus  which 
is  between  the  solution    and  the  combustion   tube  ;  drive 
out  a  few  bubbles  of  air  and  let  cool,  if  an  unequal  level 
of  the  solution  is  maintained,  the  joints  are  tight. 

(d)  Conduct  the  ignition,  heating  gradually,  and  begin- 
ning at  the  end  next  to  the  CaCl2  tube  ;  do  not  apply  heat 
to  the  substance  until  several  inches  of  CuO  are  red  hot. 
Pass  oxygen  gas  through  the  tube  if  that  method  is  em- 
ployed.    Fres.  §   178.     The  combustion  of  sugar  may  be 
completed  in  about  half  an  hour,  other  substances  require 
more  time,  especially  those  rich  in  Carbon. 

(/-)•  Aspirate  air,  or  pass  oxygen  through  the  apparatus 

slowly. 

(/)  Disconnect  the  weighed  tubes,  cool  and  weigh.  From 
the  CO2  and  the  H2O  found,  calculate  the  C  and  the  H 
respectively.  The  O  is  found  by  difference. 


IO4  QUANTITATIVE    ANALYSIS. 

Theoretical  Composition  of  Cane  Sugar. 

Ci£  144        ....        42.11 

H.,2  22       ....         6.43 

Ou          176     ....      51.46 


342  100.00 

In  the  case  of  nitrogenous  bodies  introduce  copper  turn- 
ings or  a  spiral  of  sheet  copper  in  the  end  of  the  combus- 
tion tube  next  to  the  absorption  tubes  ;  the  metallic  copper 
at  a  red  heat  reduces  any  nitric  oxide  which  may  form,  and 
the  inert  nitrogen  passes  through  the  absorption  tubes 
without  increasing  their  weight.  See  Fres.  §  183.2. 

The  difficulty  of  effecting  a  complete  oxidation  of  the 
carbon  in  organic  substances  increases,  other  things  being 
equal,  with  the  percentage  of  carbon  contained  in  the  sub- 
stance ;  the  richer  the  substance  in  carbon,  the  smaller  the 
amount  should  be  taken  for  combustion.  Moreover,  it  is 
desirable  to  graduate  the  quantity  used,  to  prevent  the  for- 
mation of  too  large  a  quantity  of  carbonic  anhydride  to 
admit  of  complete  absorption  by  the  potash  solution  ;  hence 
the  following  Table,  used  in  Prof.  A.  W.  Hoffman's  Labo- 
ratory, University  of  Berlin,  is  of  service  in  determining 
the  amount  of  substance  which  may  be  conveniently  em- 
ployed. 

Table  showing  amount  of  Substances  to  be  used  in 
Ultimate  Analysis. 

Of  substances  containing  80  percent  carbon  take  o.2oogrms. 
"  "  75         "          "         "     0.225     " 

"  "  70         "          "         "     0.250     " 

"  "  65         "          "         "     0.275     " 

"  "  60        "          "         "     0.300     " 

«  U  jj  C  «  ft  «        O.32"5         " 


DETERMINATION    OF    NITROGEN.  105 

Of  substances  containing  50  percent  carbon  take  0.350  grms. 

"  "  45       "  "         "  0.375  " 

"  "  40      "  "         «  0.400  " 

"  "  35      "  "        "  0.425  " 

"  "  30      "  "        "  0.450  " 

"  "  25      "  "        "  0.475  " 

"  20        "  "  "  0.500  " 


C.  —  Determination    of    Nitrogen   in    Potassium    Ferrocy- 
anide  by  Conversion  into  Ammonia. 

Method  of  Varrentrapp  &  Will.     See  Fres.  §  185. 

Purify  about  50  grms.  of  the  commercial  salt  by  recrys- 
tallization  ;  dry  the  crystals  on  filter  paper  and  preserve  in 
a  desiccator.  The  crystallized  salt  contains  3  molecules 
of  water. 

Principle:  When  organic  substances  are  heated  with 
hydroxides  of  the  alkaline  metals  the  carbon  is  oxidized  by 
the  oxygen  of  the  hydroxide,  and  hydrogen  is  set  free  ;  if, 
however,  nitrogen  is  present  it  combines  with  the  nascent 
hydrogen,  forming  ammonia.  (For  an  exception,  see  D.) 
By  conducting  the  operation  in  such  a  way  as  to  complete 
the  reaction,  and  collecting  all  the  ammonia  by  absorption 
in  acid  of  known  strength,  the  amount  of  nitrogen  is 
easily  calculated. 

Requisites :  The  apparatus  needed  is,  in  general,  the 
same  as  that  used  in  determination  of  C  and  of  H,  but 
a  somewhat  shorter  tube  (40  cm.)  may  be  used  ;  the  am- 
monia is  absorbed  by  normal  sulphuric  acid  placed  in  pear- 
shaped  bulbs  of  the  form  shown  in  Fig.  92,  or  Fig.  94, 
pages  443  and  445  of  Fres.  System.  The  substance  used 
to  oxidize  the  carbon  is  soda-lime,  at  present  a  commercial 


IO6  QUANTITATIVE    ANALYSIS. 

article  ;  it  should  be  heated  in  a  porcelain  dish  to   expel 
water  and  ammonia  before  using. 

Operation :  Fill  the  combustion  tube  about  one-third  full 
of  warm  soda-lime  and  let  it  cool  ;  then  mix  this  in  an 
agate  mortar  with  0.2  to  0.4  grms.  of  the  dry  ferrocyanide 
of  potassium,  and  introduce  the  mixture  again  into  the 
tube  ;  rinse  the  mortar  with  a  little  soda-lime,  and  then 
fill  the  tube  with  the  same  nearly  to  the  open  end.  Insert 
a  small  plug  of  asbestos  loosely,  attach  the  absorption  bulb 
containing  the  sulphuric  acid  by  a  well-fitting  cork,  and 
place  the  tube  in  the  combustion  furnace.  Begin  to  heat 
the  tube  at  the  end  nearest  the  cork,  and  proceed  gradu- 
ally towards  the  other  end. 

The  gas  evolved  should  bubble  quietly  through  the  ab- 
sorption tube,  and  when  it  ceases  to  pass  break  the  tail- 
piece of  the  combustion  tube,  and  aspirate  gently  through 
the  whole  apparatus. 

Detach  the  absorption  tube,  empty  its  contents  into  a 
beaker,  rinse  well,  add  a  little  litmus,  or  cochineal  solu- 
tion, and  determine,  by  means  of  normal  KHO,  the 
amount  of  acid  remaining  unneutralized  by  the  ammonia. 
For  details  of  this  process  see  Analysis  No.  12. 

Theoretical  Composition  of  Potassium  Ferrocyanide : 

C6 ;  .  .  .  17-1 

N6 19.9 

Fe 13.3 

K4 37.0 

3H20 12.7 

IOO.O 


DETERMINATION    OF    NITROGEN.  IO/ 

D.  —  Determination  of  N  from  the  Volume. 

Dumas'  method  modified  by  Melsens,  Cf.  Fres.  §  184. 
See  also  Watts'  Dictionary,  I.  242. 

When  nitrogen  exists  in  an  organic  substance  in  the  form 
of  an  oxide,  e.  g.  nitro-benzol  C«K5  (NO2),  Varrentrapp  & 
Will's  method  cannot  be  employed  because  the  oxides  of 
nitrogen  are  not  completely  converted  into  ammonia  on 
heating  with  soda  lime.  Dumas'  method  consists  in  heat- 
ing the  substance  with  oxide  of  copper,  and  measuring  the 
nitrogen  evolved  by  collecting  over  mercury.  The  process 
originally  devised  by  Dumas  necessitated  the  use  of  an  air- 
pump  to  exhaust  the  combustion  tube,  but  this  may  be 
obviated  by  following  Melsens,  who  introduces  hydro- 
sodium  carbonate  into  the  tube  which  gives  up  carbonic 
anhydride  on  heating,  and  drives  out  the  nitrogen  before  it. 

For  Melsen's  process  provide  the  following  articles  : 
(i)  A  combustion  tube  70  cm.  long. 

(2)  Mercury  trough. 

(3)  Graduated  cylinder. 

(4)  Copper  oxide. 

(5)  Solution  of  potassium  hydrate. 

(6)  Hydrosodium  carbonate. 

(7)  Connecting  tube. 

(8)  Corks,  asbestos,  rubber  tubing,  etc. 

(9)  Combustion  furnace. 

In  filling  the  combustion  tube  observe  the  following 
order:  Insert,  first,  15  cm.  of  hydrosodium  carbonate,  then 
5  cm.  of  copper  oxide,  then  15  cm.  of  copper  oxide  mixed 
with  the  substance  to  be  analyzed,  next  add  about  28  cm. 
of  copper  oxide,  insert  a  copper  spiral  5  cm.  long,  and 
lastly  a  plug  of  asbestos  in  the  remaining  2  cm.  Insert 
cork  with  connecting  tube,  and  arrange  apparatus  as  shown 
in  Pig.  91,  page  441,  of  Fres.  System. 


108  QUANTITATIVE    ANALYSIS. 

Conduct  the  operation  as  follows  :  Heat  a  portion  of  the 
NaHCO3  until  all  the  air  is  expelled  ;  test  with  a  solution 
of  KHO  in  an  inverted  test-tube  ;  then  heat  CuO  to  red- 
ness, arrange  the  graduated  cylinder  containing  KHO  solu- 
tion over  mercury,  and  heat  the  mixed  CuO  and  substance 
until  gas  ceases  to  come  off;  lastly,  expel  the  nitrogen  in 
the  combustion  tube  by  again  heating  the  NaHCO3,  some 
of  which  must  have  been  left  undecomposed.  (Oxalic  acid 
may  be  substituted  for  the  HNaCO3.  See  Thorpe,  page 
332.)  Transfer  the  graduated  cylinder  to  a  vessel  of 
water,  hold  it  so  that  the  level  of  the  water  within  the 
cylinder  and  without  is  equal,  then  read  off  the  volume  of 
the  gas  in  cubic  centimeters,  and  simultaneously  the  tem- 
perature of  the  water  and  the  height  of  the  barometer. 

Calculation  of  Results.  To  obtain  the  weight  of  nitro- 
gen from  its  volume  employ  the  following  formula  : 

Let  V  =  Volume  of  N  observed,  expressed  in  cubic  centi- 
meters. 

And  t°=  Temperature  of  the  gas. 

"     B  =  Height  of  the  barometer  expressed  in  millimeters. 
"      f  =  Tension  of  aqueous  vapor  at  the  temperature  t°, 

expressed  in  mm.  of  mercury. 
Then  if  W  =  weight  of  nitrogen  we  have  : 

W  =  .001 2566  V  — — l—-—  -^- 
i +.003671°    760 

The  constant  0.0012566  is  the  weight  in  grammes  of 
I  c.  c.  of  N  at  0°  C  and  760  mm.  The  constant  0.00367  is 
the  coefficient  of  expansion  of  gas. 

Example  :  In  an  analysis  of  Butyramide  — 

C4H70 ) 

H  v  N,  the  following  data  were  obtained  : 
H 


ANALYSIS    OF    URINE. 

0.315  grms.  of  substance  gave  43.9  c.  c.  N  at  /°=i7°3  C 
and  B  =  753.2  mm. 

First  look  out  in  a  table  the  value  of  /at  I70.3.  (Fres. 
§  !95>  Pa£e  4^1.)  We  find  (calculating  for  the  tenths  of  a 
degree)  /=  14.7. 

Now  V  =  43.9  c.  c. 

B  —  f  =753.2  mm.  —  14.7=738.5  mm. 

And  i  +  .00367  X  t°=  1.0635. 

Substituting  in  equation  : 

W  =  .0012566  V  1+-o;367to  we  have  : 


=  .0012566x43.9x738.5  =  0.0504  grms. 

1.0635X760 

.  0.0504  x  100        , 

And  —  —          -  =  1  6.00  per  cent  nitrogen. 
0.315 

Theoretical  Composition  of  Butyramide  : 


H9 

DD-* 
IO.3 

O  

1  8.4 

N 

.     .                   16  1 

IOO.O 

Analysis  No.  33.  —  URINE. 

For  brief  methods  of  analysis  consult  Dr.  George  B. 
Fowler's  "  Urine  Analysis,"  Thudicutn's  "  Manual  of  Chem- 
ical Physiology,"  pages  178-192,  and  Button's  "  Systematic 
Handbook  of  Volumetric  Analysis,"  part  vi.  §  78.  For 
figures  of  sedimentary  deposits  examine  Ultzmann  &  Hof- 
mann's  "Atlas  der  Physiologischen  und  Pathologischen 
Harnsedimente."  (44  plates.) 

The  following  works  may  also  be  studied  :  Legg's 
"  Guide  to  the  Examination  of  Urine,"  Attfield's  "  Chem- 


IIO  QUANTITATIVE    ANALYSIS. 

istry,"  F.  Hoppe-Seyler's  "  Handbuch  der  Physiol.  and 
Pathol.  Chem.  Analyse,"  Neubauer  &  Vogel's  "  Anleitung 
zur  Qualitative  und  Quantitative  Analyse  des  Harns," 
Gorup  Besanez'  "  Lehrbuch  der  Physiologischen  Chemie," 
pages  576-580,  Ultzmann  &  Hofmann's  "Anleitung  zur 
Untersuchung  des  Harns." 

Constituents  of  Urine. 

Urine,  the  secretion  of  the  kidneys,  in  a  healthy  individ- 
ual, is  a  clear,  yellowish,  fluorescent  liquid  of  a  peculiar 
odor,  saline  taste,  with  a  mean  sp.  gr.  1.020.  The  follow- 
ing are  its  normal  constituents  : 

1.  Water.  —  H2O. 

2.  Inorganic  Salts.  —  K,  Na,  NH,  Ca,  Mg,  combined  with 

HC1,  H3P04,  H2S04,  C02,  (HNO*)  and  SiO2. 

3.  Nitrogenous  crystalline  bodies.  —  Urea,  uric    acid,  hip- 

puric  acid,  creatine,  creatinine,  xanthine,  (ammonia,) 
cystine. 

4.  Non-nitrogenous  organic  bodies.  —  Sugar,  lactic,  succinic, 

oxalic,  formic,  malic,  and  phenylic  acids,  all  in  small 
quantities. 

5.  Pigments.  —  Urochrome,  urohaematin. 

6.  Albumenoid  matters. 

7.  Matters  derived  directly  from  the  food. 

Besides  these,  urine  may  contain,  under  varying  cir- 
cumstances, as  in  disease,  a  large  number  of 

8.  Abnormal  constituents. —  Blood,  pus,  mucus,  albumen, 

fibrin,  casein,  fats,  cholesterin,  leucine,  tyrosine,  allan- 
toin,  taurine,  biliary  pigments,  indigo-blue,  melanin, 
glucose,  inosite,  acetone,  butyric  acid,  benzoic  acid, 
oxaluric  acid,  taurocholic  acid,  glycocholic  acid,  and 
many  others.  (See  Watts'  Dictionary,  vol.  v.  p.  962.) 


ANALYSIS    OF    URINE.  Ill 

These  substances  do  not  occur  simultaneously  in  all 
urine,  and  many  of  them  but  rarely.  Only  those  com- 
monly determined  are  considered  in  the  Scheme 
(page  112). 


Chemical  Composition  of  Urine.     (DALTON.) 
Healthy.  —  Numbers  Approximate. 

Water 938.00 

Urea ." 30.00 

Creatine 1.25 

Creatinine     1.50 

Urate  of  soda  \ 

"     potassia     > 1.80 

"     ammonia  ) 

Coloring  matter  and  mucus 30 

Bi-phosphate  of  soda 
Phosphate  of  soda 


potassa 


12.45 


magnesia 

lime 

Chlorides  of  sodium  and  potassium  ....       7.80 
Sulphates  of  soda  and  potassa 6.90 


1000.00 


Morbid  urine  may  contain,  also  : 

Albumen,     (Bright's  disease.) 

Sugar,     (Diabetes.) 

Bile, 

Excess  of  Urea, 

Oxalate  of  calcium. 


112  QUANTITATIVE    ANALYSIS. 

Action  of  Reagents  on  Urine. 

Boiling  acid  urine  effects  no  change. 

Boiling  alkaline  urine  makes  it  turbid  if  rich  in  earthy 
phosphates. 

HNO3or  HC1  darkens  the  color,  and  throws  down  uric  acid 
on  standing. 

KHO  or  NH4HO  throws  down  earthy  phosphates. 

BaCl2  or  PbA,  in  acidified  urine,  yield  a  white  ppt.  of  sul- 
phates. 

AgNO3  white  ppt.  of  chlorides,  also  coloring  matter  and 
some  organic  substances. 

Murexid  Test.  —  Collect  some  of  the  uric  acid  thrown 
down  by  HC1,  remove  supernatant  liquid,  add  cone.  HNO3i 
and  evaporate  to  dryness.  When  cold  add  a  drop  of  NH4- 
HO.  A  purplish-crimson  color  shows  formation  of  mur- 
exid  (C8H  N606). 

Reactions  of  Urea.  —  Hg  (NO3)2  throws  down  a  gelati- 
nous white  ppt.  containing  COH4N2  .2HgO. 

Boiling  with  KHO  converted  into  NH4HO  ;  test  with 
Nessler  reagent. 

HNO3,  nitrate  of  urea  precipitates. 

NaCIO  or  NaBrO  decomposes  urea  with  evolution  of  N. 

Scheme  for  Analysis  of  Urine, 
i.  PHYSICAL  CHARACTERS. 

(a)  Odor.  —  Certain  peculiarities  in  odor  indicate  either 
nature  of  food  or  symptoms  of  disease. 

(b)  Consistence.  — Viscous  or  fluid. 

(c)  Color. — When  healthy,  urine  is  amber-colored;  when 
bilious,  brown  or  greenish. 

(d)  Specific  Gravity.  —  By  the  urinometer,  1015  to  1025 
is  marked   H.  S.,  signifying  Healthy  State.     4°  c.  makes  a 
difference  of  about  i°  in  the  reading. 


ANALYSIS    OF    URINE.  1 13 

2.  TEST  WITH  LITMUS  PAPER,  and  note  whether  acid  or 
alkaline. 

3.  POUR  A  SAMPLE  into  a  stop-cock  funnel,  and  let  stand 
12  hours.    If  a  deposit  forms,  filter,  and  examine  the  filtrate 
and  sediment  separately.     Filtered  urine  leaves  a  scum  of 
mucus.     (For  sediments,  see  Schemes,  page  117  and  118.) 

4.  DETERMINE  TOTAL  SOLIDS.     Evaporate  4  to  6  c.  c., 
weighed,  to  dryness  in  a  weighed  dish.     Dry  at  115  c.  (In- 
accurate). 

5.  ASH.     Evaporate  100  c.  c.  urine  and  ignite  residue. 

6.  DETERMINATION  OF  UREA.     CH4N2O. 

A. — Liebigs   Method. 

Principle :  Mercuric  nitrate  added  to  a  solution  of  urea 
gives  a  white,  gelatinous  ppt.  containing  i  molecule  urea, 
and  2HgO.  (Absence  of  NaCl  necessary.) 

Requirements : 

(a)  Standard  solution  Hg  (NO8)2. 

(b)  Baryta  solution. 

(c)  Carbonate  of  soda  test  paper. 

(a)  Standard    solution    of  mercuric   nitrate.      Dissolve 
72   grms.   pure   dry  HgO  in   strong   HNO3,   (50  grms.,) 
evaporate  until  syrupy,  and  dilute  to  I  litre.      If  a  yellow 
ppt.  is  produced  by  dilution,  too  little  acid  is  present.     It 
must  be  evaporated  down,  fresh  acid  added,  and  again  di- 
luted,    i  c.  c.  =  o.oi  grm.  urea.     To  test  the  strength  of 
the  mercuric  nitrate  dissolve  2  grms.  cryst.  urea  in  100  c.  c. 
water,    i  c.  c.  mercuric  solution  should  equal  o.oi  grm.  urea. 

(b)  Solution  of  Ba(NO3)2+BaH2O2.       Mix  i  part  cold 
saturated   solution   Ba(NO3)2  with  2    parts  cold  saturated 
solution  BaH2O2,  and  add  3  parts  distilled  water. 

(c}  Soda  test  paper.  Dip  a  sheet  white  filter  paper  into 
cone.  sol.  Na2  (CO3)  and  dry. 


114  QUANTITATIVE    ANALYSIS. 

Process:  Collect  the  urine  passed  during  24  hours,  and 
measure  carefully.  Place  20  c.  c.  in  a  small  beaker,  add 
20  c.  c.  barium  solution,  filter  from  the  sulphates  and  phos- 
phates. Of  the  filtrate  20  c.  c.  (containing  10  c.  c.  urine) 
are  measured  off,  a  drop  of  AgNO3  added  to  precipitate 
excess  of  chlorides,  and  then  standard  solution  of  mercuric 
nitrate  is  added  until  a  drop  of  the  mixed  solutions  gives  a 
yellow  stain  (of  mercuric  hydrate)  on  the  test  paper. 
Byasson  adds  some  of  a  solution  of  KHO  (25  grms.  to  I  litre 
water)  from  time  to  time  to  partly  neutralize  the  acid  set 
free.  The  solution  must  not  be  rendered  alkaline, 

Calculation :  Amount  urine  passed  in  24  hours  =  A  ; 
c.  c.  mercuric  solution  used  =  C  ;  each  c.  c.  being  equal 

A  x  C 
to  o.oi  grm.  urea  ;  then  -       —  =  grms.  urea  passed  in  24 

hours. 

Caution :  The  urine  must  be  free  from  phosphoric  and 
hippuric  acids.  Consult  Caldwell's  "  Agricultural  Analy- 
sis," page  220.  Urine  must  contain  2  per  cent.  urea.  Cf. 
Watts'  Diet.  vol.  v.  p.  967. 

B.  —  Daveys   Method  of  Estimating  Urea. 

Pour  a  small  quantity  of  urine  into  a  graduated  glass 
tube  one-third  full  of  mercury.  Fill  the  tube  with  a  solu- 
tion of  sodic  hypochlorite,  close  tube,  and  invert  quickly 
over  a  saturated  solution  of  NaCl.  Let  stand  several  hours 
while  the  following  reaction  ensues  : 

CH4N2O+3(NaClO)=CO2+2H2O  +  3NaCl+N2 

Read  off  the  quantity  of  N.  1.549  cubic  inches  of  N  at 
60°  Fah.  and  30"  bar.  =  i  grain  urea. 

Method  inaccurate  since  ammonia,  uric  acid,  &cv  are 
likewise  decomposed. 


ANALYSIS    OF    URINE.  1  15 

C.  —  Heintz  and  Ragskys  Method. 

First  determine  ammonia  by  precipitation  with  PtCL». 

Heat  2  to  5  c.  c.  with  equal  vol.  H2SO4  in  a  covered  cap- 
sule to  i8o°-2oo°.  Cool,  dilute  with  water,  filter,  and  de- 
termine NH3  formed  by  PtCl4.  Calculate  both  amounts  for 
100  c.  c.,  and  take  the  difference  ;  this  multiplied  by  0.13423 
gives  per  cent,  of  urea. 

Results  very  accurate. 

D.—Apjokris  Method. 

See  "American  Chemist,"  V.  431. 

Provide  the  following  apparatus  : 

(1)  A  glass  tube  30  cm.  long,  subdivided  into  30  equal 
parts,  whose  aggregate  volume  is  55  c.  c.     The  end  of  the 
tube  is  drawn  out  like  a  Mohr's  burette. 

(2)  A  wide-mouthed  gas  bottle  of  60  c.  c.  capacity. 

(3)  A  test  tube  of  10  c.  c.  capacity,  and  long  enough  to 
be  slightly  inclined  when  introduced  into  the  gas  bottle. 

The  principle  of  the  process  is  based  upon  the  following 
equation  : 

H4)  +  3(CaBr2O2)=3CaBr2-f-2CO2+N4 


To  make  the  hypobromite  solution  take  loogrms.  NaHO, 
250  c.  c.  H2O,  and  add  25  c.  c.  bromine  ;  agitate  and  set 
aside  for  use. 

Process  :  Into  a  glass  cylinder  containing  water  the  tube 
(i)  is  depressed  till  the  zero  mark  and  surface  of  water 
coincide.  15  c.  c.  hypobromite  solution  (100  grms.  NaHO, 
250  c.  c.  H2O,  25  c.  c.  Br)  are  placed  in  (2)  and  the  test- 
tube  containing  the  urine  is  introduced  carefully  to  avoid 
spilling  its  contents.  The  flask  is  closed  by  a  perforated 


Il6  QUANTITATIVE    ANALYSIS. 

stopper  which  is  connected  by  tubing  with  the  measuring 
tube.  The  urine  is  now  mixed  with  the  hypobromite,  and 
the  disengaged  nitrogen  is  driven  into  the  measuring  tube. 
The  tube  is  now  levelled  to  relieve  hydrostatic  pressure, 
and  the  volume  of  nitrogen  read  off.  Since  55  c.  c.  equal 

0.15  grm.  of  urea,  a  single  division  corresponds  to 

=0.005  grm-  urea. 

(0.15  grm.  urea  gives  55  c.  c.  nitrogen  at  60°  Fah.  and 
30°  bar.) 

7.  DETERMINATION  OF  ACTUAL  AMMONIA.   Take  20  c.  c. 
filtered  urine  and  treat  by  Schlosing's  method. 

The  NH3  is  expelled  by  milk  of  lime,  and  absorbed  by 
standard  acid,  in  the  cold  under  a  bell  jar.  For  details  see 
Fres.  §  99,  3  b.  p.  158.  (Human  urine  contains  0.078  to 
0.143  per  cent.) 

8.  DETERMINATION     OF     ALBUMEN.       Measure    urine 
passed  in   24  hours.     Drop  50  c.  c.,  one  c.  c.  at  a  time, 
into    I  ounce  boiling  distilled  water  in  a    porcelain  dish. 
If  the  urine  was  alkaline  add  a  drop  of  acetic  acid,  avoid 
excess.      Allow  the  coagulated    albumen    to  settle,    filter 
through  a  weighed  filter,  and  wash  well.     Dry  at  100°  C, 
and  weigh. 

9.  DETERMINATION   OF   SUGAR.     Dilute  urine  5  or   10 
times,  and  apply  Fehling's  solution  as  in  grape  sugar.     See 
Analysis  No.  35,  Raw  Sugar. 

10.  DETERMINATION  OF  PHOSPHORIC  ACID.     To  50  c.  c. 
filtered   urine   add   5    c.  c.   sodic   acetate  and   titrate  with 
uranic    acetate.      For   details    see    Sutton's    "  Volumetric 
Analysis." 

11.  DETERMINATION    OF   URIC  ACID.  —  To   200   c.    c. 
urine  add   10  c.  c.  HC1,   stand  48    hours  in  a  cool  place, 


DETERMINATION    OF    URINE. 


117 


filter  on  a  very  small  weighed  filter.  Wash-water  should 
not  exceed  30  c.  c.  If  more  is  necessary  add  0.045  mgm. 
uric  acid  for  each  c.  c.  additional.  (Albumen  must  first  be 
removed  by  coagulation.)  Dry  at  ioo°c.  and  weigh. 

12.    TESTS  FOR  BILE. 

(1)  Place  a  little  urine  on  a  white  plate,  add  HNO3.     A 
peculiar  play  of  colors  —  green,  yellow,  violet,  &c.  —  occurs 
if  coloring  matter  of  bile  is  present. 

(2)  Agitate  concentrated  urine  with  boiling  ether.      If 
bile  is  present  the  ether  solution  will  be  greenish-yellow. 

(3)  Add  baric  acetate  to  urine,  treat  the  ppt   with  alco- 
hol, decompose   it  with  HC1,  and  evaporate  the  liquid  to 
dryness.     Water  will  dissolve  out  in  the  residue  coloring 
matter  of  the  bile. 

(4)  Pettenkofers  Test. — Mix  fluid  with  one-half  vol.  H2SO4, 
avoiding  rise  of  temperature  ;   add  a  little  powdered  cane 
sugar  ;  mix  and  add  more  H2SO4.     Liberation  of  cholalic 
acid  produces  a  purplish-red  coloration  ;  this  gives  a  pecul- 
iar absorption  spectrum.     See  Thudichum's  "  Manual." 

Scheme  for  analysis  of  Urinary  Sediments.    (ATTFIELD.) 

Warm  the  sediment  with  the  supernatant  urine,  and  filter. 


INSOLUBLE. 

Phosphates,    oxalate   of  calcium    and    uric   acid. 
Warm  with  acetic  acid,  and  filter. 

SOLUBLE. 

Urates  of  Ca,    N;i, 
and   NH4,  — 
chiefly  of  Na. 
They  are  re-depos- 
ited as  the  liquid 
cools,  and  if  suffi- 
cient in  quantity 
may    be    exam- 
ined     for      uric 
acid    and    bases 
by    usual    tests. 

INSOLUBLE. 

Oxalate  of   calcium    and  uric  acid. 
Warm  with  HC1,  and  filter. 

SOLUBLE. 

Phosphates. 
AddNH4HO, 
and    exam- 
ine ppt. 
for  P2O5, 
CaO   and 
MgO. 

INSOLUBLE. 

Uric    acid.       Apply 
murexid  test. 

SOLUBLE. 

Oxalate  of  cal- 
cium.    May 
be    pptd.  by 
N!!4HO. 

Note.  —Urates   are  often  of  a   pink  or    red  color,  owing  to  the  pig- 
ment purpurine.     This  is  soluble  in  alcohol. 


QUANTITATIVE    ANALYSIS. 


Scheme  for  Determination  of  Urinary  Sediments  by  Chemi- 
cal Tests.     (ATTFIELD.) 


The  sediment   is   white;    warm 
with   the    supernatant    urine 
and  filter. 

The  sediment  is  colored 

and 
crystalline 
uric  acid. 

and  amorphous 
easily  soluble 
on  heating 
urates. 

and 
amorphous, 
slowlv  solu- 
ble on  heat- 
ing.    Urates 
colored  by 
purpurine. 

Solution 
contains 
urates. 

Residue 
Treat  with  ammonia. 

Solution       Residue 
contains  Treat  with 
cystine.       acetic   acid. 

Residue 
oxalate  and 
oxa  lit  rate 
of  calcium. 

Solution. 
Add  NH4 
HO  white 
ppt.  of 
earthy 
phos- 
phates. 

Analysis  No.  34.  —  MILK. 

A.  —  Determination  of  Water. 

Wash  quartz  sand  thoroughly  with  HC1  and  water,  and 
ignite.  Put  about  one-quarter  inch  of  this  sand  in  a  plati- 
num pan,  weigh,  and  pour  on  3  to  5  grms  milk.  Dry  at  100° 
C.  to  constant  weight. 

B.— Determination  of  Butter. 

Break  up  the  cake  from  residue  A  and  wash  the  butter 
out  with  ether  into  a  weighed  beaker,  evaporate  the  ether 
and  weigh  the  butter. 

C.  —  Determination  of  Sugar. 

Collect  the  residue  from  B  on  a  dried  and  weighed  filter, 
dry  it  at  100°  C.,  boil  it  four  or  five  times  with  fresh  por- 
tions (i5oc.  c.  each)  of  80  per  cent,  alcohol,  and  dry  the 
insoluble  residue  at  iocT  C.  and  weigh  on  a  tared  filter. 
The  loss  of  weight  gives  the  sugar  approximately.  Or 
determine  sugar  as  under  grape  sugar,  Analysis  No.  35. 


DETERMINATION    OF    SUGAR.  119 

A  convenient  apparatus  for  the  extraction  of  sugar  is 
described  by  Prof.  S.  W.  Johnson,  in  Am.  J.  of  Sci.  (3)xiii. 
page  196(1877). 

D.  —  Determination  of  total  Non- volatile  Matter. 

Evaporate  10  to  20  grms.  milk  to  dryness,  with  the 
addition  of  a  little  acetic  acid,  and  ignite  the  residue  in  a 
muffle  furnace,  at  the  lowest  possible  temperature. 

E.  —  Determination  of  Protein  Compounds. 

Subtract  the  sum  of  the  butter,  sugar,  and  ash  from  the 
total  dry  substance,  and  the  remainder  is  chiefly  casein. 

For  other  methods,  see  "  A  Method  for  the  Analysis  of 
Milk,"  by  E.  H.  von  Baumhauer,  Am.  Chem.,  Vol.  VII.,  191. 

Analysis  No.  35.  —  RAW  SUGAR. 


A.  —  Determination  of  Moisture. 

Heat  a  weighed  amount  of  sugar  at  1 10°  until  it  no 
longer  loses  in  weight.  Loss  =  moisture. 

B. —  Determination  of  Ash. 

Weigh  off  ten  grms.  in  a  platinum  dish.  Either  burn  the 
sugar  direct,  or  add  a  few  drops  of  cone.  H2SO4  and  heat 
very  cautiously  in  a  gas  muffle.  Weigh  the  ash. 

The  two  methods  do  not  give  results  at  all  concordant  ; 
the  latter  is  the  French  method,  and  the  results  are  called 
"  the  salts,"  after  subtracting  one-ninth,  but  this  is  seldom 
correct,  though  the  ash  burns  very  white. 

C. —  Determination  of  Grape  Sugar. 
C6H1206,  H20 

(i)    Qualitative    reactions.      Glucose     is    colored    dark- 


I2O  QUANTITATIVE   ANALYSIS. 

brown  when  heated  with  a  strong  solution  of  sodic  hy- 
drate. It  dissolves  in  cold  cone.  H2SO4  without  being 
blackened.  [Cane  sugar  blackens.] 

If  a  cone,  solution  of  glucose  is  mixed  with  cobaltic 
nitrate,  and  a  small  quantity  of  fused  NaHO,  the  solution 
remains  clear  on  being  boiled  ;  if  very  concentrated  it  de- 
posits a  light-brown  ppt. 

[Cane  sugar  solutions  similarly  treated  give  a  violet  ppt., 
which  turns  green  on  standing]. 

BaH2O2  added  to  an  alcoholic  solution  of  glucose  forms 
a  white  ppt. 

If  a  little  caustic  soda  is  added  to  a  solution  of  glucose, 
and  then  drop  by  drop  a  dilute  solution  of  CuSO4,  a  deep- 
blue  liquid  forms  ;  after  some  time  in  the  cold,  but  imme- 
diately if  heated,  a  yellowish  or  red  ppt.  of  hydrated  cuprous 
oxide  is  deposited.  yooVoo  °f  glucose  may  be  easily  de- 
tected ;  y/oo^/oTo  st^  gives  a  red  tint  to  the  solution. 

Cupric  acetate  is  similarly  reduced.  Potassio-tartrate  of 
copper  acts  likewise. 

(2)  Quantitative  estimation,  i  eq.  glucose  will  reduce 
10  eq.  of  cupric  oxide  to  cuprous  oxide. 

Preparation  of  Fehlings  Solution.     (Fres.,  §  250.) 

Dissolve  exactly  34.639  grms.  pure  dry  CuSO4  in  about 
200  c.  c.  water.  In  another  vessel  dissolve  173  grms.  C.  P. 
Rochelle  salts  (C4H4K  NaO6-f-4H2O)  in  480  c.  c.  pure  sodi- 
um hydrate  solution  having  a  sp.  gr.  1.14. 

Mix  the  solutions  and  dilute  to  exactly  1000  c.  c.  loc.  c. 
of  this  solution  contains  0.34639  grms.  CuSO4  and  corre- 
sponds to  0.050  grms.  anhydrous  glucose.  Keep  in  the 
dark.  On  boiling  with  four  vols.  of  water,  it  should  give 
no  precipitate. 


DETERMINATION  OF  GRAPE  SUGAR.         121 

The  solution  of  glucose  should  not  contain  more  than 
|  per  cent,  glucose  ;  if  stronger,  dilute. 

Performance  of  Analysis  : 

Run  exactly  10  c.  c.  of  the  copper  solution  into  a  small 
flask,  add  40  c.  c.  water,  (or  a  dilute  solution  of  NaHO.) 
heat  to  boiling  and  run  into  the  solution  the  liquid  con- 
taining the  glucose,  slowly  and  gradually,  from  an  accurate 
burette.  Continue  until  the  last  shade  of  bluish  green 
disappears,  and  a  small  portion  of  liquid  filtered,  gives  no 
reaction  with  H2S,  nor  with  HC2H3O2  and  K4Fe2Cy6. 

Calculation.  Since  we  took  10  c.  c.,  Fehling's  solution, 
corresponding  to  0.050  grms.  anhydrous  glucose,  we  read  ofif 
the  number  of  c.  c.  of  glucose  solution  taken  ;  this  shows  us 
how  much  of  the  substance  contains  50  grms.  grape  sugar. 

Example.  —  Used  9.  5  c.  c.  solution  containing  glucose  : 

9.5  :  .05  =  loo  :  x 
If  solution  was  diluted,  then  .rX^=per  cent,  glucose. 

This  method  may  be  applied  to  cane  sugar,  by  first  con- 
verting it  into  grape  sugar  by  boiling  one  to  two  hours 
with  dilute  H2SO4  (i  part  acid  5  parts  water).  This  is  not 
very  accurate,  owing  to  formation  of  caramel.  Milk  sugar 
reduces  Fehling's  solution  direct,  but  in  another  propor- 
tion, 100  glucose  =  134  milk  sugar. 

D.  —  Determination  of  Crystalizable  Cane  Sugar. 
Weigh  out  x  grms.*  of  sugar  or  syrup,  add  water  so  that 
the  whole  will  form  about  80  c.  c.     Dissolve  and  add  for 

*  The  value  of  #  depends  upon  the  instrument  employed.  Instruc- 
tions usually  accompany  a  sacchari meter. 


122  QUANTITATIVE   ANALYSIS. 

syrup  5  to  10  c.  c.  basic  acetate  of  lead  ;  for  raw  sugar  less  ; 
for  pure  sugar,  none.  Dilute  to  100  c.  c.  ;  pour  into  a 
beaker,  and  add  pulverized  bone-black,  and  filter  ;  do  not 
wash.  Fill  the  tube  of  a  Soleil  or  Dubosq  Saccharimeter 
with  this  solution,  perfectly  full,  insert  the  tube,  and 
observe  the  transition  tint.  For  details,  see  Atkinson's 
translation  of  Ganot's  Physics,  §'613.  Cf.  Fownes'  Chem- 
istry, p.  84,  and  Watts'  Diet.  iii.  673-5. 

Analysis  of  a  sample  of  RAW  SUGAR. 

Water,          ...                 .  2.07 

Ash, 1.58 

Grape  Sugar,       .         .         .         .         .         1.82 
Cane  Sugar, 86.00 

Analysis  No.  37.  —  PETROLEUM. 

For  information  as  to  the  composition  and  refining  of 
petroleum,  the  products  which  it  yields  by  distillation,  and 
the  methods  of  testing  kerosene,  see  Dr.  C.  F.  Chandler's 
"  Report  on  Petroleum  Oil "  in  the  "  American  Chemist," 
Vol.  II.  pp.  409,  446,  and  Vol.  III.  pp.  20  and  41. 

A.— Distillation  of  Petroleum. 

The  method  of  examining  crude  petroleum  for  determi- 
nation of  its  commercial  value,  is  not  that  of  fractional 
distillation  in  its  true,  scientific  sense,  but  consists  in  a 
process  of  distillation  which  separates  the  liquid  into  a 
certain  number  of  al'quot  parts,  having  determinable  den- 
sities, and  flashing  points  ;  and  the  value  of  the  sample 
depends  upon  the  proportion  of  the  light  and  heavy  pro- 
ducts. 

The  process  of  distillation  is  conducted  as  follows.  Se- 
lect a  tubulated  retort  of  strong  glass,  free  from  flaws,  and 


DISTILLATION     OF    PETROLEUM.  123 

of  about  500  c.  c.  capacity  ;  connect  this  with  a  Liebig's 
condenser,  and  arrange  for  distilling  in  the  usual  manner. 
Through  the  tubulus  of  the  retort  insert  a  thermometer. 
Provide  ten  glass  cylinders  of  50  to  75  c.  c.  in  capacity, 
and  mark  each  with  a  file,  so  as  to  show  the  volume  occu- 
pied by  25  c.  c.  of  liquid.  These  cylinders  are  to  serve  as 
recipients  of  the  distillate. 

Pour  250  c.  c.  crude  petroleum  into  the  retort,  and  apply 
heat  very  gently  at  first,  increasing  gradually,  and  finally 
heating  until  the  residue  in  the  retort  is  coked.  Collect 
25  c.  c.  of  the  distillate  in  the  first  cylinder,  and  note  the 
temperature  indicated  by  the  thermometer  in  the  retort ; 
collect  the  second  25  c.  c.  in  another  recipient,  note  also 
temperature,  and  continue  in  this  manner,  changing  the 
recipient  for  every  25  c.  c.  until  the  whole  liquid  has  dis- 
tilled over. 

B.  —  Examination  of  the  Distillates. 

Determine  the  sp.  gr.  of  each  distillate  by  floating  in  it 
a  small  Baumo  Hydrometer,  note  the  color  of  each  sam- 
ple, and  determine  its  flashing  point  by  means  of  Taglia- 
bue's  "Open  Tester,"  a  figure  and  description  of  which  are 
found  on  page  41,  Vol.  III.  of  the  "American  Chemist." 

To  test  the  flashing  point,  proceed  as  follows  :  pour  a 
small  quantity  of  the  sample  to  be  examined  into  the  open 
cup,  which  is  surrounded  by  a  vessel  of  water.  Light  the 
lamp  beneath  and  apply  heat  very  gradually  ;  the  tempera- 
ture should  not  rise  faster  than  two  degrees  a  minute. 
The  thermometer  bulb  should  dip  beneath  the  surface  of 
the  oil.  .  From  time  to  time  test  the  inflammable  vapors 
which  arise  from  the  surface  of  the  oil,  using  a  small  flame, 
flitting  it  quickly  across  the  surface,  and  noting  simultane- 
ously the  height  of  the  thermometer  at  the  moment  of 
Record  results  with  each  distillate. 


124 


QUANTITATIVE    ANALYSIS. 


Example.  —  The  following  report  of  an  actual  distilla- 
tion shows  how  the  results  may  be  reported.  This  distilla- 
tion was  accompanied  with  the  phenomena  technically 
called  "  cracking,"  by  which  the  heavier  hydrocarbons  split 
up  into  lighter  ones. 

No.  of 
fraction. 

I. 

2. 

3- 
4- 
5- 
6. 

7 
8. 

9- 
10. 


Colorless, 


Light  yellow, 


Yellow, 
Dark  yellow, 
Deeper  " 
Green, 
Black, 


Temperature 

Sp.  Gr. 

Flashing  Point. 

Fahr. 

Beaume". 

Fahr. 

I42°-224° 

64 

20° 

224  -298 

60 

48 

298   -404 

55 

102 

404   -458 

51 

147 

458  -532 

45 

208 

532-       ? 

42 

254 

40 

204 

42 

44 


The  tenth  product  was  coke  left  in  the  retort. 


82 


Fig.  6  shows  the  disposition  of  apparatus  at  the  commencement  of  the  distillation  ;  so  soon 
as  the  lighter  products  have  passed  over,  the  bulb  tube  a  c  must  be  removed  and  connection 
made  with  the  condenser  by  a  short  bent  tube. 


APPENDIX. 


TABLE    I. 

THE   ELEMENTS,    THEIR    SYMBOLS,   AND   ATOMIC 
WEIGHTS. 


Name. 

Symbol. 

Atomic 
Weight. 

Name. 

Symbol. 

Atomic 
Weight. 

Aluminium  .  .  . 
Antimony  .... 
Arsenic  .... 
Barium  .... 
Bismuth  .... 
Boron  .  . 

Al 
Sb 
As 
Ba 
Bi 
Bo 

274  [ 

122.    ; 
75- 
137- 

210. 
1  1 

Manganese  .  .  . 
Mercury  .... 
Molybdenum  .  . 
Nickel  .... 
Nitrogen  .... 
Osmium 

Mn 
Hg 
Mo 
Ni 
N 
Os 

55- 

2OO. 
96. 
58.8 
14. 
TOO  ""> 

Bromine  .... 
Cadmium  .... 
Caesium  .... 
Calcium  .... 
Carbon  ..... 

Br 
Cd 

Cs 
Ca 

c 

80. 
112. 

133- 
40. 
12. 

Oxygen  .... 
Palladium  .  .  . 
Phosphorus  .  .  . 
Platinum  .  .  . 
Potassium  . 

0 
Pd 
P 
Pt 

K 

»yy«* 

1  6. 
106.6 

31- 
197.4 

•3Q    T 

Cerium  .... 
Chlorine  „  .  .  . 
Chromium  .  .  . 
Cobalt 

Ce 
Cl 
Cr 
Co 

92.  : 

35-5 
52.2 
58  8  ! 

Rhodium  .  .  . 
Rubidium  .  ."  . 
Ruthenium  .  .  . 
Selenium  .  .  . 

Rh 
Rb 
Ru 

Se 

JV-1 
1044 

854 
1044 

Columbium  .  .  . 
Copper 

Cb 

Cu 

94- 

hi  A 

Silicon  .... 
Silver 

Si 
Ag 

28. 

108 

Didymium      .     .     . 
Erbium      .  '  . 
Fluorine     .... 
Gallium      .... 
Glucinum        .     .     . 
Gold                .     . 

D 
E 
F 
Ga 
Be 
Au 

.  uj  4 

95- 
170.5 
19. 
69.9 
94 

IQ7 

Sodium  .... 
Strontium  .  .  . 
Sulphur  .... 
Tantalum  .  .  . 
Tellurium  .  .  . 
Thallium 

Na 
Sr 
S 
Ta 
Te 
Tl    . 

23- 
87.6 

32. 
182. 
128. 

1Q  A 

Hydrogen  .... 
I  ndiuiYi 

H 
In 

•y/' 

T  -7-j   A 

Thorium  .... 
Tin  .  .  .  .  . 

Th 
Sn 

235- 

118 

Iodine  
Iridium  .... 
Iron  ...... 

Lanthanum  .  .  . 
Lead  .  . 

T 

Ir 
Fe 
La 
Pb 

127. 
198. 
56..  i 
93-6 

°O7 

Titanium 
Tungsten      . 
Uranium  .... 
Vanadium     .     .     . 
Yttrium    . 

Ti 
W 
U 

V 
Y 

50. 
184. 
240. 
51.2 
61.7 

Lithium  .... 
Magnesium  .  .  . 

Li 
Mg 

7- 
24. 

Zinc  
Zirconium 

Zn 
Zr 

65.2 
89.6 

APPENDIX. 

TABLE    II. 
PRECIPITATING   VALUE    OF    COMMON    REAGENTS. 

Solutions  of  reagents  being  prepared  of  the  strength  recommended 
by  Fresenius  (see  Fres.  Oual.  Anal,  §  17  to  §  85,  b,  Johnson's  edition 
of  1875),  the  amount  of  a  reagent  required  for  precipitation  may  be 
calculated  from  the  following  table  : 

One  cubic  centimetre  of  Will  precipitate 

Dilute  sulphuric  acid 0.231  grm.  Ba. 

Barium  chloride 0.032  "  SO3. 

Hydrodisodic  phosphate      ....  o.ou  "  MgO. 

Magnesia  mixture 0.024  "  P-Oj 

Ammonium  molybdate o.ooi  "  PoO;. 

Ammonium  oxalate 0.016  "  CaO. 

Argentic  nitrate o.oio  "  Cl. 


TABLE   III. 

DIAMETER   OF    FILTERS    AND    WEIGHTS    OF    FILTER 
ASHES;    SWEDISH    PAPER. 

Weight  of  Ash. 


Filter  No. 

Diameter. 

Acid. 

Alkaline. 

I      .      .      . 

70  mm. 

0.0004  grm. 

0.0014 

2     .      .      . 

104      " 

0.0007     " 

O.OO27 

3   •    • 

,       122       " 

0.00  1  1       " 

0.0043 

147    "  0.0016    "  0.0062 


APPENDIX. 

TRINITY    COLLEGE. 

HARTFORD,....  ...  188 


Report  of 
Analysis  of 

Determination  of 
Grammes  taken  : 
Method  of  Analysis. 


Actual  Calculated  Theoretical 

Precipitates.       Weights.       Constituents.          Weights.         Percentages.       Percentages. 


Special  Remarks. 


[This  is  a  reduced   fac-simile  of  the  reporting  blank,  measuring  S  by  10  inches,  de- 
scribed on  page  17.] 


ERRATA. 


First  table  on  page  96  should  read  as  follows : 

Combine  K     as  K,  SO4 

"  excess  of         K      i;  KC1 

Cl     "  Na  Cl 

Na    "  Na,SO4. 

"        '<         Cl     "  Mg  CL 

S04  "      Ca  SO,. 
Ca     "      Ca  CO,. 
"  Mg    "      Mg  CO3. 

Page  9,  line   16,  for  Ag  C  read  Ag  Cl. 

Page  ii,  line  20,  for  Beispeilen  read  Beispielen. 


INDEX. 


Acidimetry,  45. 

Albumen,  determination  of,  in  urine,  116. 
Alkalies,  determination  of,  in  potable  water, 
92. 

in  feldspar,  estimation  of,  56. 
Alkalimetry,  42. 

Alloys,  determination  of  two  metals  in,  100. 
Alum,  ammonia-iron,  analysis  of,  20. 
Alumina,  iron  and  phosphoric  acid,  75. 
Alvargonzalez,  determination  of    total  car- 
bon, 81. 

Ammonia-iron-alum,  analysis  of,  20. 
Ammonia,  determination  of,  in  guano,  88. 
Ammonio-magnesic    phosphate,     properties 

of,  19. 
Ammonium,  gravimetric  determination  of,  20. 

phospho-molybdate,  properties  of,  70. 
Analysis,  organic,  101. 
Analyses,  calculations  of,  15. 

reporting  of,  17. 

Antimony,  determination  of,  51. 
Apjohn's  method  of  estimating  urea,  115. 
Arsenical  nickel  ore,  analysis  of,  86. 
Ash,  estimation  of,  in  coal,  37. 

Baric  chloride,  analysis  of,  13. 
Barium,  determination  of,  14. 

sulphate,  properties  of,  18. 
Bell's  determination  of  total  carbon  in  pig- 
iron,  81. 

Bile,  tests  for,  in  urine,  117. 
Bleaching  powder,  constitution  of,  47. 

reactions  of,  48. 

valuation  of,  49. 
Bronze,  analysis  of,  35. 
Butter,  determination  of,  in  milk,  118. 
Butyramide,  estimation  of  nitrogen  in,  107. 

Cairns'  determination  of  graphite  in  pig-iron, 

78. 

Calcium,  determination  of,  31. 
Calculation  of  results  of  analyses,  15. 


Calorific  power  of  coal,  39. 
Cane  sugar,  analysis  of,  101. 

determination  of,  121. 
Carbon,  estimation  of,  in  coal,  39. 

total,  determination  of,  in  pig-iron,  79. 

ultimate  determination  of,  in  sugar,  102. 
Carbonic  anhydride,  determination  by  direct 
weight,  34. 

determination  by  loss,  33. 
Chandler's  analysis  of  Croton  Water,  98. 
Chloride  of  lime,  valuation  of,  49. 
Chlorimetry,  47. 
Chlorine,  determination  of,  13. 

determination  of,  in  potable  water,  92. 
Chromic  iron  ore,  analysis  of,  54. 
Clark's  soap  test  for  potable  water,  93. 
Coal,  proximate  analysis  of,  36. 
Cobalt,  determination  of,  in  nickel  ore,  86. 
Combustions,  process  of  conducting,  103. 
Copper,  electrolytic  estimation  of,  35,  39. 

estimation  of,  in  a  silver  coin,  29. 

pyrites,  analysis  of,  39. 

Davey's  method  of  estimating  urea,  114. 
Distillation  of  petroleum,  122. 
Dolomite,  analysis  of,  30. 
Drown's   determination   of  sulphur   in   pig- 
iron,  83. 

Eggertz'  determination  of  graphite   in  pig- 
iron,  77. 

determination  of  sulphur  and  phosphorus 
in  pig-iron,  82. 

Elliott's    determination   of  total  carbon   in 
pig-iron,  79. 

Fehling's  solution,  preparation  of,  120. 

Feldspar,  analysis  of,  56. 

Ferrocyanide  of  potassium,  determination  of 

nitrogen  in,  105. 
Flight's  method  of  separating  iron,  alumina, 

and  phosphoric  acid,  75. 
Fusion  of  an  iron  ore,  66. 

125 


126 


INDEX. 


Glucose,  estimation  of,  119. 
Grape  sugar,  determination  of,  119. 
Graphite,  determination  of,  in  pig-iron,  76. 
Guano,  analysis  of.  88. 

Heintz  and   Ragsky's  method  of  estimating 

urea,  115. 

Hematite,  analysis  of,  62. 
Hydrochloric  acid,  valuation  of,  46. 
Hydrodisodic  phosphate,  analysis  of,  27. 
Hydrogen,  determination  of,  in  sugar,  102. 

Iron  and  titanium,  determination  of,  74. 
basic  acetate  of,  53,  68. 
determination  of,   in  ammonia-iron-alum, 

21. 

determination  of,  in  a  titaniferous  ore,  68, 

7»- 

determination  of,  by  precipitation,  22. 
determination  of,  in  hematite,  62. 
ore,  titaniferous,  analysis  of,  63. 
slag,  analysis  of,  60. 
volumetric  determination  of,  22,  71. 

Koninck  and  Dietz'  determination  of  sulphur 
in  pig-iron,  84. 

Lead,  estimation  of,  in  a  silver  coin,  29. 
Liebig's  method  of  estimating  urea,  113. 
Liquids,  specific  gravity  of,  99. 
Litmus  solution,  preparation  of,  42.  . 

Magnesic  sulphate,  analysis  of,  18. 
Magnesium,  separation  from  calcium,  30. 
Manganese,  estimation  of,  56. 

Gibbs'  method  of  estimation,  70. 
Marguerite's    method  for  determination  of 

iron,  22. 

Melsens'  determination  of  nitrogen,  107. 
Milk,  analysis  of,  izS. 
Moisture,  determination  of,  in  coal,  36. 
Molybdenum,  use  of,  in  estimation  of  phos- 
phoric acid,  69. 

Nickel  ore,  arsenical,  analysis  of,  86. 
Nitrogen,  determination  of,  by  Varrentrapp 

and  Will's  method,  105. 
Melsens'  determination  of,  107. 
Normal  solutions,  41. 

Organic  analysis,  101. 
matter  in  potable  water,  94. 


Pearl-ash,  valuation  of,  45. 

Penot's  method  for  valuation  of  chloride  of 

lime,  49. 
Permanganate  of  potassium,  standardization 

of,  25. 

Petroleum,  distillation  of,  122. 
Phosphoric  acid,  determination  of,  28. 
determination  of,  in  guano,  89. 
determination  of,  by  molybdenum,  69. 
Flight's  method  of  separation  from  iron, 

75- 

insoluble,  determination  of,  in  superphos- 
phates, 90. 

reduced,  determination  of,  in  superphos- 
phates, 90. 
Phosphorus,   determination   of,  in   pig  iron, 

76,  82. 

Pig-iron,  analysis  of,  76. 
Potassium  chloride,  analysis  of,  26. 
ferrocyanide,  determination  of  nitrogen  in, 

105. 

gravimetric  estimation  of,  26. 
permanganate,  solution  of,  22. 
Pyrolusite,  analysis  of,  56. 

Raw  sugar,  analyses  of,  119. 
Reporting  analyses,  17. 
Reverted  phosphoric  acid,  determination  of, 
91. 

Salammoniac,  action  of  nitric  acid  on,  32. 
Schlosing's  determination  of  ammonia,  88. 
Silica,  determination  of,  in  soluble  silicates, 

59- 

determination  of,  in  slag,  61. 

separation  of,  from  titanium,  64. 
Silicates,  analysis  of  soluble,  59. 
Silver  coin,  analysis  of,  29. 
Slag,  analysis  of  iron,  60. 
Soap  test  for  potable  water,  93. 
Soda  ash,  valuation  of,  44. 
Sodium,  determination  of,  27. 
Specific  gravities  of  solids  and  liquids,  99. 
Standard  solutions,  42. 

Sugar,  determination  of  ash  in  raw  sugar, 
119. 

determination  of,  in  milk,  118. 

ultimate  analysis  of,  101. 
Sulphur,  determination  of,  in  pig-iron,  82. 

estimation  of,  in  coal,  37. 
Sulphuric    acid,    gravimetric    determination 
of,  18. 


INDEX. 


127 


Sulphuric  acid  in  potable  water,  determina- 
tion of,  92. 
Superphosphate  of  lime,  analysis  of,  90. 

Testing  petroleum,  122. 

Tin,  determination  of,  in  type  metal,  51. 

determination  of,  in  bronze,  35. 
Titaniferous  iron  ore,  analysis  of,  63. 
Titanium,  estimation  of,  in  iron  ore,  74. 
Titration,  residual  method  of,  45. 
Type  metal,  analysis  of,  31. 

Urea,  determination  of,  Liebig's  method,  113. 

Apjohn's  method,  115. 

Davey's  method,  114. 
Urinary  sediments,  scheme  for  analysis  of, 

117. 
Urine,  analysis  of,  109. 

composition  of,  in. 


Varrentrapp  and  Will's  estimation  of  nitro- 
gen, 105. 

Vinegar,  analysis  of,  46. 
Volatile  matter,  estimation  of,  in  coal,  37. 
Volumetric  analysis,  general  notes  on,  40. 
estimation  of  nitrogen,  107. 

Water  analysis,  calculation  of  results,  95. 

determination  of,  by  direct  weight,  28. 

determination  of,  by  ignition,  15,  28. 

determination  of,  in  milk,  118. 

potable,  analysis  of,  91. 
Weyl's  determination  of  total  carbon  in  pig- 
iron,  82. 

Zinc,  determination  of,  in  bronze,  36. 
ore,  analysis  of,  53. 


14  DAY  USE 

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